Please describe the problem:
After upgrading to git commit 073457de, gimp-gap failed building libgapvidapi as follows:

Making all in libgapvidapi
/usr/bin/gcc-4.0 -DHAVE_CONFIG_H -I. -I.. -I.. -I/opt/local/include/glib-2.0 -I/opt/local/lib/glib-2.0/include -I/opt/local/include   -I/opt/local/include/gimp-2.0 -I/opt/local/include/glib-2.0 -I/opt/local/lib/glib-2.0/include -I/opt/local/include -I/opt/local/include/gtk-2.0 -I/opt/local/lib/gtk-2.0/include -I/opt/local/include/atk-1.0 -I/opt/local/include/cairo -I/opt/local/include/pango-1.0 -I/opt/local/include/pixman-1 -I/opt/local/include/freetype2 -I/opt/local/include/libpng12   -I/opt/local/var/macports/build/_Volumes_wdc-320_opt_macports_trunk_dports_graphics_gimp-gap-devel/work/gimp-gap-devel-2.5.0.840/extern_libs/ffmpeg -I/opt/local/var/macports/build/_Volumes_wdc-320_opt_macports_trunk_dports_graphics_gimp-gap-devel/work/gimp-gap-devel-2.5.0.840/extern_libs/ffmpeg/libavcodec -I/opt/local/var/macports/build/_Volumes_wdc-320_opt_macports_trunk_dports_graphics_gimp-gap-devel/work/gimp-gap-devel-2.5.0.840/extern_libs/ffmpeg/libavformat -I/opt/local/var/macports/build/_Volumes_wdc-320_opt_macports_trunk_dports_graphics_gimp-gap-devel/work/gimp-gap-devel-2.5.0.840/extern_libs/ffmpeg/libavutil -I/opt/local/var/macports/build/_Volumes_wdc-320_opt_macports_trunk_dports_graphics_gimp-gap-devel/work/gimp-gap-devel-2.5.0.840/extern_libs/ffmpeg/libavdevice   -I../libgapbase -I/opt/local/include -DLOCALEDIR=\""/opt/local/share/locale"\" -I/opt/local/include -DGIMP_DISABLE_DEPRECATED  -O2 -Wall -fPIC -MT gap_vid_api.o -MD -MP -MF .deps/gap_vid_api.Tpo -c -o gap_vid_api.o gap_vid_api.c
In file included from gap_vid_api.c:77:
gap_vid_api_util.c: In function 'GVA_md5_string':
gap_vid_api_util.c:232: warning: implicit declaration of function 'gimp_md5_get_digest'
In file included from gap_vid_api.c:78:
gap_vid_api_vidindex.c: In function 'GVA_load_videoindex':
gap_vid_api_vidindex.c:397: warning: implicit declaration of function 'gap_file_get_mtime'
In file included from gap_vid_api.c:725:
/opt/local/var/macports/build/_Volumes_wdc-320_opt_macports_trunk_dports_graphics_gimp-gap-devel/work/gimp-gap-devel-2.5.0.840/extern_libs/ffmpeg/libavformat/avformat.h: At top level:
/opt/local/var/macports/build/_Volumes_wdc-320_opt_macports_trunk_dports_graphics_gimp-gap-devel/work/gimp-gap-devel-2.5.0.840/extern_libs/ffmpeg/libavformat/avformat.h:117: error: redefinition of 'struct AVPacket'
/opt/local/var/macports/build/_Volumes_wdc-320_opt_macports_trunk_dports_graphics_gimp-gap-devel/work/gimp-gap-devel-2.5.0.840/extern_libs/ffmpeg/libavformat/avformat.h:163: error: redefinition of typedef 'AVPacket'
/opt/local/include/libavcodec/avcodec.h:935: error: previous declaration of 'AVPacket' was here
/opt/local/var/macports/build/_Volumes_wdc-320_opt_macports_trunk_dports_graphics_gimp-gap-devel/work/gimp-gap-devel-2.5.0.840/extern_libs/ffmpeg/libavformat/avformat.h:212: error: static declaration of 'av_free_packet' follows non-static declaration
/opt/local/include/libavcodec/avcodec.h:2750: error: previous declaration of 'av_free_packet' was here
In file included from gap_vid_api.c:726:
gap_vid_api_ffmpeg.c: In function 'p_wrapper_ffmpeg_get_video_chunk':
gap_vid_api_ffmpeg.c:762: warning: assignment discards qualifiers from pointer target type
gap_vid_api_ffmpeg.c: In function 'p_private_ffmpeg_get_next_frame':
gap_vid_api_ffmpeg.c:1048: warning: 'avcodec_decode_video' is deprecated (declared at /opt/local/include/libavcodec/avcodec.h:3215)
gap_vid_api_ffmpeg.c:1147: warning: implicit declaration of function 'img_convert'
gap_vid_api_ffmpeg.c: In function 'p_wrapper_ffmpeg_seek_frame':
gap_vid_api_ffmpeg.c:1327: warning: implicit declaration of function 'gap_base_get_gimprc_gboolean_value'
gap_vid_api_ffmpeg.c: In function 'p_reset_proberead_results':
gap_vid_api_ffmpeg.c:1355: warning: implicit declaration of function 'gap_base_get_gimprc_int_value'
gap_vid_api_ffmpeg.c: In function 'p_seek_native_timcode_based':
gap_vid_api_ffmpeg.c:2576: warning: unused variable 'secs'
gap_vid_api_ffmpeg.c:2809: warning: assignment makes integer from pointer without a cast
gap_vid_api_ffmpeg.c:2810: warning: assignment makes integer from pointer without a cast
gap_vid_api_ffmpeg.c:2467: warning: unused variable 'l_readsteps'
gap_vid_api_ffmpeg.c:2466: warning: unused variable 'l_rc_rd'
gap_vid_api_ffmpeg.c: In function 'p_read_audio_packets':
gap_vid_api_ffmpeg.c:4303: warning: 'avcodec_decode_audio2' is deprecated (declared at /opt/local/include/libavcodec/avcodec.h:3158)
gap_vid_api_ffmpeg.c: In function 'p_timecode_check_and_log':
gap_vid_api_ffmpeg.c:4643: warning: unused variable 'diff_dts'
gap_vid_api_ffmpeg.c: In function 'p_save_video_analyse_results':
gap_vid_api_ffmpeg.c:4755: warning: unused variable 'ii'
gap_vid_api_ffmpeg.c: In function 'p_frame_nr_to_timecode':
gap_vid_api_ffmpeg.c:5043: warning: format '%ld' expects type 'long int', but argument 2 has type 'gint32'
gap_vid_api_ffmpeg.c: In function 'p_probe_timecode_offset':
gap_vid_api_ffmpeg.c:5240: warning: format '%ld' expects type 'long int', but argument 4 has type 'int'
gap_vid_api_ffmpeg.c:5240: warning: format '%ld' expects type 'long int', but argument 5 has type 'gint32'
gap_vid_api.c: In function 'p_gva_deinterlace_drawable':
gap_vid_api.c:1962: warning: unused variable 'col'
gap_vid_api.c:1959: warning: unused variable 'dest_buffer'
make[2]: *** [gap_vid_api.o] Error 1
make[1]: *** [all-recursive] Error 1
make: *** [all] Error 2

gap_vid_api.c is including /opt/local/include/libavcodec/avcodec.h which is installed by a MacPorts version of ffmpeg (svn 18784) which is more recent than and API incompatible with ffmpeg 0.5.

Removing the conflicting ffmpeg installation solves the problem although this
is not an acceptable solution for MacPorts.


API incompatible with ffmpeg 0.5

Steps to reproduce:
Attempt to build gimp-gap 073457de on MacPorts with conflicting MacPorts ffmpeg installed.


Actual results:
gap_vid_api.c includes avcodec.h from the system installed copy rather than
the local embedded copy.

Expected results:
gap_vid_api.c should always use the local embedded copy of ffmpeg include files
even if another copy of ffmpeg is installed in system include paths.

Does this happen every time?
yes

Other information:
The problem occurs because elements that contain the system include path are
ordered before the local include path in the Makefile.

Attached is a patch that reorders the include paths in libgapvidapi/Makefile.am
to put the local ffmpeg include paths before other elements that may include
the system path.

This allows gimp-gap to build correctly without regard to the installation
of other MacPorts versions of ffmpeg.