I just tested the 1.5.3 binaries and my link pass broke. Using 1.5.3 I
get unresolved externals on things like _MPI_NULL_COPY_FN. On 18.104.22.168
it's fine. I did a dumpbin on libmpi.lib for both versions, and in
1.5.3 there's upper-case symbols for _OMPI_C_MPI_NULL_COPY_FN, but not
_MPI_NULL_COPY_FN. In the 22.214.171.124 libmpi.lib there's symbols for both.