Comment 7 for bug 340408

I don't know... maybe you can try to purge the old versions
sudo dpkg --purge libx264-54 libx264-57 libx264-59

the test ./configure does is:
require libx264 x264.h x264_encoder_open -lx264 -lm &&
                      { check_cpp_condition x264.h "X264_BUILD >= 65" ||
                        die "ERROR: libx264 version must be >= 0.65."; }

so look in your /usr/include/x264.h if you see the line:
#define X264_BUILD 65

if it's present simply overwrite the old check with this:
require libx264 x264.h x264_encoder_open -lx264 -lm