Reduce n_compute_elements and n_io_elements to avoid OpenMPI bug

The OpenMPI library has a bug on macOS in which large messages
cause the code to hang; see, e.g.,
open-mpi/ompi#6568

This commit reduces the size of some arrays used in unit tests
for SMIOL_create_decomp to work around this issue.

smiol_runner.F90

@@ -608,8 +608,8 @@ function test_decomp(test_log) result(ierrcount)
 
         ! Large number of Compute and IO Elements
         write(test_log,'(a)',advance='no') 'Everything OK for SMIOLf_create_decomp large number of elements: '
-        n_compute_elements = 10000000
-        n_io_elements = 10000000
+        n_compute_elements = 1000000
+        n_io_elements = 1000000
         allocate(compute_elements(n_compute_elements))
         allocate(io_elements(n_io_elements))
         ierr = SMIOLf_create_decomp(context, n_compute_elements, compute_elements, n_io_elements, io_elements, decomp)

smiol_runner.c

@@ -703,8 +703,8 @@ int test_decomp(FILE *test_log)
 
 	/* Create and Free Decomp with large amount of elements */
 	fprintf(test_log, "Everything OK (SMIOL_create_decomp) with large amount of elements: ");
-	n_compute_elements = 100000000;
-	n_io_elements = 100000000;
+	n_compute_elements = 1000000;
+	n_io_elements = 1000000;
 	compute_elements = malloc(sizeof(SMIOL_Offset) * n_compute_elements);
 	io_elements = malloc(sizeof(SMIOL_Offset) * n_io_elements);
 	ierr = SMIOL_create_decomp(context, n_compute_elements, compute_elements, n_io_elements, io_elements, &decomp);