svq1.h where this function is used. Fixes the warning:
libavcodec/svq3.c:862: warning: implicit declaration of function ‘ff_svq1_packet_checksum’
Originally committed as revision 15737 to svn://svn.ffmpeg.org/ffmpeg/trunk
Consistently apply this rule: the guard name is obtained from the
filename by stripping the leading "lib", converting '/' and '.' to
'_' and uppercasing the resulting name. Guard names in the root
directory have to be prefixed by "FFMPEG_".
Originally committed as revision 15120 to svn://svn.ffmpeg.org/ffmpeg/trunk
