CONFIG_RV20_ENCODER when also checking for CONFIG_H263_ENCODER.
The RV10/RV20 encoders depend on the H.263 encoder.
Originally committed as revision 19593 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
