I'd tried to build 1.11.91 from tarballs today and got a lot of errors when building qtkitvideosrc.

libtool: compile:  gcc -DHAVE_CONFIG_H -I. -I../.. -Dgst_core_media_buffer_new=gst_core_media_buffer_priv_new -Dgst_core_media_buffer_get_type=gst_core_media_buffer_priv_get_type -Dgst_core_media_buffer_get_pixel_buffer=gst_core_media_buffer_priv_get_pixel_buffer -Dgst_core_video_buffer_new=gst_core_video_buffer_priv_new -Dgst_core_video_buffer_get_type=gst_core_video_buffer_priv_get_type -I/opt/oblong/deps-64-11/include -I../../gst-libs -I../../gst-libs -fobjc-arc -mmacosx-version-min=10.8 -I/opt/oblong/deps-64-11/include/gstreamer-1.0 -I/opt/oblong/deps-64-11/include/glib-2.0 -I/opt/oblong/deps-64-11/lib/glib-2.0/include -D_REENTRANT -DGST_USE_UNSTABLE_API -DG_THREADS_MANDATORY -DG_DISABLE_CAST_CHECKS -Wall -Wmissing-declarations -Wredundant-decls -Wwrite-strings -Wformat-nonliteral -Wformat-security -Winit-self -Wmissing-include-dirs -Wno-multichar -g -I/opt/oblong/deps-64-11/include/gstreamer-1.0 -I/opt/oblong/deps-64-11/include/glib-2.0 -I/opt/oblong/deps-64-11/lib/glib-2.0/include -D_REENTRANT -I/opt/oblong/deps-64-11/include/gstreamer-1.0 -I/opt/oblong/deps-64-11/include/glib-2.0 -I/opt/oblong/deps-64-11/lib/glib-2.0/include -D_REENTRANT -g -O2 -MT libgstapplemedia_la-avfassetsrc.lo -MD -MP -MF .deps/libgstapplemedia_la-avfassetsrc.Tpo -c avfassetsrc.m  -fno-common -DPIC -o .libs/libgstapplemedia_la-avfassetsrc.o
libtool: compile:  gcc -DHAVE_CONFIG_H -I. -I../.. -Dgst_core_media_buffer_new=gst_core_media_buffer_priv_new -Dgst_core_media_buffer_get_type=gst_core_media_buffer_priv_get_type -Dgst_core_media_buffer_get_pixel_buffer=gst_core_media_buffer_priv_get_pixel_buffer -Dgst_core_video_buffer_new=gst_core_video_buffer_priv_new -Dgst_core_video_buffer_get_type=gst_core_video_buffer_priv_get_type -I/opt/oblong/deps-64-11/include -I../../gst-libs -I../../gst-libs -fobjc-arc -mmacosx-version-min=10.8 -I/opt/oblong/deps-64-11/include/gstreamer-1.0 -I/opt/oblong/deps-64-11/include/glib-2.0 -I/opt/oblong/deps-64-11/lib/glib-2.0/include -D_REENTRANT -DGST_USE_UNSTABLE_API -DG_THREADS_MANDATORY -DG_DISABLE_CAST_CHECKS -Wall -Wmissing-declarations -Wredundant-decls -Wwrite-strings -Wformat-nonliteral -Wformat-security -Winit-self -Wmissing-include-dirs -Wno-multichar -g -I/opt/oblong/deps-64-11/include/gstreamer-1.0 -I/opt/oblong/deps-64-11/include/glib-2.0 -I/opt/oblong/deps-64-11/lib/glib-2.0/include -D_REENTRANT -I/opt/oblong/deps-64-11/include/gstreamer-1.0 -I/opt/oblong/deps-64-11/include/glib-2.0 -I/opt/oblong/deps-64-11/lib/glib-2.0/include -D_REENTRANT -g -O2 -MT libgstapplemedia_la-avsamplevideosink.lo -MD -MP -MF .deps/libgstapplemedia_la-avsamplevideosink.Tpo -c avsamplevideosink.m  -fno-common -DPIC -o .libs/libgstapplemedia_la-avsamplevideosink.o
qtkitvideosrc.m:187:11: error: 'retain' is unavailable: not available in automatic reference counting mode
  [device retain];
          ^
/usr/include/objc/NSObject.h:36:1: note: 'retain' has been explicitly marked unavailable here
- (instancetype)retain OBJC_ARC_UNAVAILABLE;
^
qtkitvideosrc.m:187:11: error: ARC forbids explicit message send of 'retain'
  [device retain];
   ~~~~~~ ^
qtkitvideosrc.m:203:13: error: 'release' is unavailable: not available in automatic reference counting mode
    [device release];
            ^
/usr/include/objc/NSObject.h:37:1: note: 'release' has been explicitly marked unavailable here
- (oneway void)release OBJC_ARC_UNAVAILABLE;
^
qtkitvideosrc.m:203:13: error: ARC forbids explicit message send of 'release'
    [device release];
     ~~~~~~ ^
qtkitvideosrc.m:214:12: error: 'release' is unavailable: not available in automatic reference counting mode
  [session release];
           ^
/usr/include/objc/NSObject.h:37:1: note: 'release' has been explicitly marked unavailable here
- (oneway void)release OBJC_ARC_UNAVAILABLE;
^
qtkitvideosrc.m:214:12: error: ARC forbids explicit message send of 'release'
  [session release];
   ~~~~~~~ ^
qtkitvideosrc.m:217:10: error: 'release' is unavailable: not available in automatic reference counting mode
  [input release];
         ^
/usr/include/objc/NSObject.h:37:1: note: 'release' has been explicitly marked unavailable here
- (oneway void)release OBJC_ARC_UNAVAILABLE;
^
qtkitvideosrc.m:217:10: error: ARC forbids explicit message send of 'release'
  [input release];
   ~~~~~ ^
qtkitvideosrc.m:220:11: error: 'release' is unavailable: not available in automatic reference counting mode
  [output release];
          ^
/usr/include/objc/NSObject.h:37:1: note: 'release' has been explicitly marked unavailable here
- (oneway void)release OBJC_ARC_UNAVAILABLE;
^
qtkitvideosrc.m:220:11: error: ARC forbids explicit message send of 'release'
  [output release];
   ~~~~~~ ^
qtkitvideosrc.m:223:11: error: 'release' is unavailable: not available in automatic reference counting mode
  [device release];
          ^
/usr/include/objc/NSObject.h:37:1: note: 'release' has been explicitly marked unavailable here
- (oneway void)release OBJC_ARC_UNAVAILABLE;
^
qtkitvideosrc.m:223:11: error: ARC forbids explicit message send of 'release'
  [device release];
   ~~~~~~ ^
qtkitvideosrc.m:336:14: error: 'release' is unavailable: not available in automatic reference counting mode
  [queueLock release];
             ^
/usr/include/objc/NSObject.h:37:1: note: 'release' has been explicitly marked unavailable here
- (oneway void)release OBJC_ARC_UNAVAILABLE;
^
qtkitvideosrc.m:336:14: error: ARC forbids explicit message send of 'release'
  [queueLock release];
   ~~~~~~~~~ ^
qtkitvideosrc.m:338:10: error: 'release' is unavailable: not available in automatic reference counting mode
  [queue release];
         ^
/usr/include/objc/NSObject.h:37:1: note: 'release' has been explicitly marked unavailable here
- (oneway void)release OBJC_ARC_UNAVAILABLE;
^
qtkitvideosrc.m:338:10: error: ARC forbids explicit message send of 'release'
  [queue release];
   ~~~~~ ^
qtkitvideosrc.m:439:23: error: cast of C pointer type 'CVImageBufferRef' (aka 'struct __CVBuffer *') to Objective-C pointer type 'id' requires a bridged cast
  [queue insertObject:(id)videoFrame
                      ^~~~~~~~~~~~~~
qtkitvideosrc.m:439:24: note: use __bridge to convert directly (no change in ownership)
  [queue insertObject:(id)videoFrame
                       ^
                       __bridge 
qtkitvideosrc.m:439:27: note: use CFBridgingRelease call to transfer ownership of a +1 'CVImageBufferRef' (aka 'struct __CVBuffer *') into ARC
  [queue insertObject:(id)videoFrame
                          ^
                          CFBridgingRelease( )
qtkitvideosrc.m:455:11: error: cast of Objective-C pointer type 'id _Nullable' to C pointer type 'CVPixelBufferRef' (aka 'struct __CVBuffer *') requires a bridged cast
  frame = (CVPixelBufferRef) [queue lastObject];
          ^~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~
qtkitvideosrc.m:455:12: note: use __bridge to convert directly (no change in ownership)
  frame = (CVPixelBufferRef) [queue lastObject];
           ^
           __bridge 
qtkitvideosrc.m:455:30: note: use CFBridgingRetain call to make an ARC object available as a +1 'CVPixelBufferRef' (aka 'struct __CVBuffer *')
  frame = (CVPixelBufferRef) [queue lastObject];
                             ^
                             CFBridgingRetain( )
qtkitvideosrc.m:583:3: error: 'NSAutoreleasePool' is unavailable: not available in automatic reference counting mode
  OBJC_CALLOUT_BEGIN ();
  ^
qtkitvideosrc.m:574:3: note: expanded from macro 'OBJC_CALLOUT_BEGIN'
  NSAutoreleasePool *pool; \
  ^
/System/Library/Frameworks/Foundation.framework/Headers/NSAutoreleasePool.h:10:12: note: 'NSAutoreleasePool' has been explicitly marked unavailable here
@interface NSAutoreleasePool : NSObject {
           ^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.
make[3]: *** [libgstapplemedia_la-qtkitvideosrc.lo] Error 1
make[3]: *** Waiting for unfinished jobs....