adds configure test for MPICH datatype bug

config/checkdoc/test_mpich_datatype.txt

+
+Your MPI library is unable to handle certain dervied MPI datatypes correctly.
+
+It is strongly recommended to switch to a version of MPI that is not affected
+with the issue.
+
+Alternatively, you can disable this test with the configure argument
+"--disable-mpi-checks" but this might result into a non-working YAC build.

config/checksrc/test_mpich_datatype.c

+#include <mpi.h>
+
+#include <inttypes.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+/* unfortunately GCC 11 cannot handle the literal constants used for
+ * MPI_STATUSES_IGNORE by MPICH */
+#if (__GNUC__ == 11 || __GNUC__ == 12) && defined MPICH
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wstringop-overread"
+#pragma GCC diagnostic ignored "-Wstringop-overflow"
+#endif
+
+// acx_mpi_job_count=1
+
+struct datatype {
+  int i;
+  uint64_t ui64;
+};
+
+static MPI_Datatype gen_ddt(MPI_Comm comm) {
+
+  struct datatype dummy;
+  MPI_Datatype ddt;
+  MPI_Type_create_struct(
+    2, (int[]){1,1},
+    (MPI_Aint[])
+      {(MPI_Aint)((void*)&(dummy.i) - (void*)&dummy),
+       (MPI_Aint)((void*)&(dummy.ui64) - (void*)&dummy)},
+    (MPI_Datatype[]){MPI_INT, MPI_UINT64_T}, &ddt);
+  MPI_Type_commit(&ddt);
+  return ddt;
+}
+
+int main (void) {
+
+  MPI_Init(NULL, NULL);
+
+  int rank;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+
+  MPI_Datatype ddt = gen_ddt(MPI_COMM_WORLD);
+
+  int count = 20705;
+  // in my tests for counts < 17403 the bug does not occure
+  // int count = 17403;
+  size_t buffer_size = count * sizeof(struct datatype);
+  struct datatype * send_buffer = malloc(buffer_size);
+  struct datatype * recv_buffer = malloc(buffer_size);
+
+  memset(send_buffer, 0, buffer_size);
+  memset(recv_buffer, 0, buffer_size);
+
+  int tag = 0;
+  MPI_Sendrecv(send_buffer, count, ddt, rank, tag,
+               recv_buffer, count, ddt, rank, tag, 
+               MPI_COMM_WORLD, MPI_STATUS_IGNORE);
+
+  free(recv_buffer);
+  free(send_buffer);
+
+  MPI_Type_free(&ddt);
+
+  MPI_Finalize();
+
+  return EXIT_SUCCESS;
+}