Fixes warnings:
libavcodec/mpegvideo_enc.c:574: warning: implicit declaration of function
'ff_match_2uint16'
libavcodec/ituh263enc.c:143: warning: implicit declaration of function
'ff_match_2uint16'
libavcodec/svq1enc.c:97: warning: implicit declaration of function
'ff_match_2uint16'


git-svn-id: file:///var/local/repositories/ffmpeg/trunk@21133 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b