MPI-5 ABI fix for MPI_THREAD_* constants (noncontiguous)

Nobody has claimed this yet.

MPI never required the thread constants to be a contiguous set, although that happened to be true in MPICH and Open MPI. With the MPI-5 ABI, they will not be contiguous, so the following patch is required to fix Quicksilver.

```patch
diff --git a/src/utilsMpi.cc b/src/utilsMpi.cc
index 811d892..d0e51de 100644
--- a/src/utilsMpi.cc
+++ b/src/utilsMpi.cc
@@ -11,13 +11,21 @@

#ifdef HAVE_MPI

+static const char* mpiThreadLevelName(int level)
+{
+ if (level == MPI_THREAD_SINGLE) return "MPI_THREAD_SINGLE";
+ if (level == MPI_THREAD_FUNNELED) return "MPI_THREAD_FUNNELED";
+ if (level == MPI_THREAD_SERIALIZED) return "MPI_THREAD_SERIALIZED";
+ if (level == MPI_THREAD_MULTIPLE) return "MPI_THREAD_MULTIPLE";
+
+ return "unknown MPI thread level";
+}
+
void mpiInit( int *argc, char ***argv)
{

#ifdef HAVE_OPENMP
{ // limit scope
- char const* const provided_string[4] = \
- {"MPI_THREAD_SINGLE","MPI_THREAD_FUNNELED","MPI_THREAD_SERIALIZED","MPI_THREAD_MULTIPLE"};
int provided, required = MPI_THREAD_FUNNELED;

int err = MPI_Init_thread(argc, argv, required, &provided);
@@ -26,12 +34,12 @@ void mpiInit( int *argc, char ***argv)
int rank = -1;
mpiComm_rank(MPI_COMM_WORLD, &rank);
if (rank == 0)
- fprintf(stdout,"MPI Initialized : %s\n", provided_string[provided]);
+ fprintf(stdout,"MPI Initialized : %s\n", mpiThreadLevelName(provided));

if ((required > MPI_THREAD_SINGLE) && (required > provided))
{
printf("MPI-OpenMP Error.\n\tCode requires %s thread support. MPI library provides %s support.\n",
- provided_string[required],provided_string[provided]);
+ mpiThreadLevelName(required), mpiThreadLevelName(provided));
qs_assert(false);
}
} // limit scope

```

Start in src/utilsMpi.cc, focusing on mpiInit and the MPI thread-level reporting around MPI_Init_thread. Replace the contiguous-index lookup with explicit handling for MPI_THREAD_SINGLE, MPI_THREAD_FUNNELED, MPI_THREAD_SERIALIZED, and MPI_THREAD_MULTIPLE as shown in the issue. Done means Quicksilver reports and validates thread levels correctly when MPI-5 constants are noncontiguous.

Written by the indexing model from the issue text.