Fix some compiler warnings

[devreal]

Random selection of compiler warnings found with Clang 17.

The warnings addressed here:

pialltoallw_f.c: In function ‘ompi_ialltoallw_f’:
pialltoallw_f.c:110:12: warning: ‘c_sdispls’ may be used uninitialized in this function [-Wmaybe-uninitialized]
     c_ierr = PMPI_Ialltoallw(sendbuf,
     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
                              OMPI_ARRAY_NAME_CONVERT(sendcounts),
                              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                              OMPI_ARRAY_NAME_CONVERT(sdispls),
                              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                              c_sendtypes,
                              ~~~~~~~~~~~~
                              recvbuf,
                              ~~~~~~~~
                              OMPI_ARRAY_NAME_CONVERT(recvcounts),
                              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                              OMPI_ARRAY_NAME_CONVERT(rdispls),
                              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                              c_recvtypes, c_comm, &c_request);
                              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
pialltoallw_f.c:110:12: warning: ‘c_sendcounts’ may be used uninitialized in this function [-Wmaybe-uninitialized]

../../../../ompi/mca/coll/base/coll_base_allreduce.c: In function ‘ompi_coll_base_allreduce_intra_allgather_reduce’:
../../../../ompi/mca/coll/base/coll_base_allreduce.c:1284:9: warning: unused variable ‘rank’ [-Wunused-variable]
     int rank = ompi_comm_rank(comm);
         ^~~~

../../../../../opal/mca/smsc/xpmem/smsc_xpmem_component.c: In function ‘mca_smsc_xpmem_component_query’:
../../../../../opal/mca/smsc/xpmem/smsc_xpmem_component.c:119:19: warning: variable ‘low’ set but not used [-Wunused-but-set-variable]
         uintptr_t low, high;
                   ^~~

[bosilca]

The commits are not signed. Don't merge before fixing this.

[bosilca]

sign the commits

[devreal]

They are signed with a Signed-off-by line but no cryptographically. I can try to get me the verified tag but I don't think we have required that in the past

[bosilca]

I thought we did, but after checking the last set of commits it appears we haven't. Most of the regular contributors are either "Verified" or nothing. But somehow you are specifically marked as "Unverified".

[devreal]

I think I have enabled that warning for my commits. Just added my new email address to my GPG key and now it shows as Verified (applies to my prior commits as well)

[jsquyres]

@devreal is right: we've just required the signoff line in the commit message -- we haven't required cryptographically-verified commits.

[jsquyres]

@bosilca You have a negative review based on asking @devreal to sign his commits. Can you change that to a positive review?

Thanks!