configure: Update required x264 version

configure accepted old versions which then caused a build failure
later. Update required version number from 59 to 65.

configure

@@ -6799,7 +6799,7 @@ if test "$_x264" = auto ; then
   cat > $TMPC << EOF
 #include <inttypes.h>
 #include <x264.h>
-#if X264_BUILD < 59
+#if X264_BUILD < 65
 #error We do not support old versions of x264. Get the latest from SVN.
 #endif
 int main(void) { x264_encoder_open((void*)0); return 0; }