src/pmdas/mmv/src/mmv.c: avoid compiler warnings when printing size_t values
src/pmdas/mmv/src/mmv.c: avoid compiler warnings when printing size_t values

It is dangerous to make assumptions about the size and type of a
size_t.

adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp