Convert the predefined MPI object padding to a fixed number of bytes
(vs. a multiple of sizeof(void*)) so that the padding is the same size
between 32 and 64 bit builds. I.e., we won't have a situation where
we've run out of padding in 32 bit builds but still have more space
available in 64 bit builds.
Fixes#3610
Signed-off-by: Jeff Squyres <jsquyres@cisco.com>
d520c24f3a