While installing, libx264 with mp4 support, we hit this error.
/usr/bin/ld: cannot find -lgpac_static
collect2: ld returned 1 exit status
make: *** [libx264.so.60] Error 1
To solve it,
Install libgpac (rpm or from source)
ranlib /usr/lib/libgpac_static.a
ldconfig -v