This patch fixes#7147 by preventing overflow when multiplying
the count and the blocklen. The count reflects MPI count and is
therefore bound to the size of an int (it is an uint32_t) while the
blocklen can be merged together to represent the largest contiguous
memory layout and it is therefore promoted to a size_t.
Signed-off-by: George Bosilca <bosilca@icl.utk.edu>
(cherry picked from commit 59fb02618e75022e3cd137199e3d390757e3c7e0)
a1b4e697f5