make ff_rate_control_init() bail out if rc_strategy==1 and lavc wasn't compiled with xvid support.
make ff_rate_control_init() bail out if rc_strategy==1 and lavc wasn't
compiled with xvid support.


git-svn-id: a4d7c1866f8397a4106e0b57fc4fbf792bbdaaaf@5176 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

prajnashi/ffmpeg,prajnashi/ffmpeg,prajnashi/ffmpeg,prajnashi/ffmpeg