When building gst-plugins-base without gtk 2.12 installed the following error appears. When I install gtk 2.12 it builds fine. 

Seems like the tests shouldn't be build when there isn't gtk 2.12 installed on the system.

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mkdir .libs
cc -I../../gst-libs -I../../gst-libs -D_REENTRANT -I/usr/local/include/gstreamer-0.10 -I/usr/local/include/glib-2.0 -I/usr/local/lib/glib-2.0/include -I/usr/local/include/libxml2 -I/usr/local/include -Wall -Wdeclaration-after-statement -g -O2 -fno-strict-aliasing -pipe -O2 -I/usr/local/include -pthread -o .libs/stress-xoverlay stress_xoverlay-stress-xoverlay.o -pthread  -L/usr/local/lib /usr/local/lib/libSM.so /usr/local/lib/libICE.so /usr/local/lib/libX11.so /usr/local/lib/libXau.so /usr/local/lib/libXdmcp.so -lrpcsvc ../../gst-libs/gst/interfaces/.libs/libgstinterfaces-0.10.so /usr/local/lib/libgstreamer-0.10.so /usr/local/lib/libgobject-2.0.so /usr/local/lib/libgmodule-2.0.so /usr/local/lib/libgthread-2.0.so -pthread /usr/local/lib/libxml2.so -lz -lm /usr/local/lib/libglib-2.0.so /usr/local/lib/libintl.so /usr/local/lib/libpcre.so /usr/local/lib/libiconv.so  -Wl,--rpath -Wl,/usr/local/lib
creating stress-xoverlay
/bin/sh /usr/ports/multimedia/gstreamer-plugins/work/gnome-libtool --tag=CC   --mode=link cc  -O2 -fno-strict-aliasing -pipe -O2 -I/usr/local/include  -L/usr/local/lib  -pthread -o test-colorkey   
cc -O2 -fno-strict-aliasing -pipe -O2 -I/usr/local/include -pthread -o test-colorkey  -L/usr/local/lib -pthread  
cc: No input files specified
gmake[3]: *** [test-colorkey] Error 1
gmake[3]: Leaving directory `/usr/ports/multimedia/gstreamer-plugins/work/gst-plugins-base-0.10.21/tests/icles'
gmake[2]: *** [all-recursive] Error 1
gmake[2]: Leaving directory `/usr/ports/multimedia/gstreamer-plugins/work/gst-plugins-base-0.10.21/tests'
gmake[1]: *** [all-recursive] Error 1
gmake[1]: Leaving directory `/usr/ports/multimedia/gstreamer-plugins/work/gst-plugins-base-0.10.21'
gmake: *** [all] Error 2
*** Error code 2