Check requirement for libx264 version in configure using

require_cpp_condition().

Originally committed as revision 15598 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -1740,7 +1740,8 @@ enabled libschroedinger && add_cflags $(pkg-config --cflags schroedinger-1.0) \
                         && require libschroedinger schroedinger/schro.h schro_init $(pkg-config --libs schroedinger-1.0)
 enabled libtheora  && require  libtheora theora/theora.h theora_info_init -ltheora -logg
 enabled libvorbis  && require  libvorbis vorbis/vorbisenc.h vorbis_info_init -lvorbisenc -lvorbis -logg
-enabled libx264    && require  x264 x264.h x264_encoder_open -lx264 -lm
+enabled libx264    && require x264 x264.h x264_encoder_open -lx264 -lm \
+                   && require_cpp_condition x264 x264.h "X264_BUILD >= 65"
 enabled libxvid    && require  Xvid xvid.h xvid_global -lxvidcore
 enabled mlib       && require  mediaLib mlib_types.h mlib_VectorSub_S16_U8_Mod -lmlib