The multimedia/transcode port fails to build, complaining that it can't find
avcoec_thread_init in -lavcodec:

checking ffmpeg/avcodec.h usability... yes
checking ffmpeg/avcodec.h presence... yes
checking for ffmpeg/avcodec.h... yes
checking libavcodec/avcodec.h usability... yes
checking libavcodec/avcodec.h presence... yes
checking for libavcodec/avcodec.h... yes
checking for pkgconfig support for libavcodec... gnome-config: not found
no
checking how to determine LIBAVCODEC_CFLAGS... user
checking how to determine LIBAVCODEC_LIBS... user
checking for avcodec_thread_init in -lavcodec... no
checking for pkgconfig support for libmpeg2... gnome-config: not found
no

Looking in the config.log file, I see:

configure:27697: checking for avcodec_thread_init in -lavcodec
configure:27732: cc -o conftest -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -O2 -fno-strict-aliasing -pipe -march=athlon-xp -I/compat/linux/usr/include/divx -isystem /usr/include -isystem /usr/local/include -L/usr/local/lib -L/usr/local/lib conftest.c -lavcodec -L/usr/local/lib -lavcodec -lm -lz   >&5
/usr/local/lib/libavcodec.so: undefined reference to `pthread_create'
/usr/X11R6/lib/libgpac.so.1: undefined reference to `pthread_attr_init'
/usr/X11R6/lib/libgpac.so.1: undefined reference to `pthread_exit'
/usr/X11R6/lib/libgpac.so.1: undefined reference to `pthread_cancel'
/usr/X11R6/lib/libgpac.so.1: undefined reference to `pthread_setschedparam'
/usr/X11R6/lib/libgpac.so.1: undefined reference to `pthread_attr_setdetachstate'
/usr/local/lib/libavcodec.so: undefined reference to `pthread_join'


libavcodec indeed does not appear to be linked with pthread libraries:

$ ldd /usr/local/lib/libavcodec.so
/usr/local/lib/libavcodec.so:
        liba52.so.0 => /usr/X11R6/lib/liba52.so.0 (0x8877d000)
        libavutil.so.1 => /usr/X11R6/lib/libavutil.so.1 (0x88789000)
        libz.so.3 => /lib/libz.so.3 (0x88795000)
        libm.so.4 => /lib/libm.so.4 (0x887a6000)
        libtheora.so.0 => /usr/X11R6/lib/libtheora.so.0 (0x887bc000)
        libvorbisenc.so.2 => /usr/X11R6/lib/libvorbisenc.so.2 (0x887fe000)
        libvorbis.so.4 => /usr/X11R6/lib/libvorbis.so.4 (0x888f9000)
        libx264.so.50 => /usr/X11R6/lib/libx264.so.50 (0x88920000)
        libogg.so.5 => /usr/local/lib/libogg.so.5 (0x889be000)
        libgpac.so.1 => /usr/X11R6/lib/libgpac.so.1 (0x889c3000)
        libssl.so.4 => /usr/lib/libssl.so.4 (0x88c29000)
        libcrypto.so.4 => /lib/libcrypto.so.4 (0x88c5b000)

$ pkg_which /usr/local/lib/libavcodec.so
ffmpeg-2008.07.27_2

How-To-Repeat: portupgrade multimedia/transcode