This fixes a build problem for MIPS architecture that looks like this:

libavcodec/mips/h264dsp_msa.c:2498:6: error: conflicting types for
‘ff_weight_h264_pixels16_8_msa’
 void ff_weight_h264_pixels16_8_msa(uint8_t *src, int stride,

This bug was introduced by commit bc26fe89:

  avcodec/h264: Use ptrdiff_t for (bi)weight functions

That commit changed the data type of some function parameters in some
function definitions. However, the implementation of those functions in
libavcodec/mips/h264dsp_msa.c wasn't changed accordingly.
Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>