Do not use PPM in check programs if USE_MPI is not defined.

This is the first step towards building serial versions of tests also when MPI is enabled.

tests/pio_write.c

@@ -16,10 +16,10 @@
 #ifdef USE_MPI
 #include <mpi.h>
 #include <yaxt.h>
-#endif
 #ifdef HAVE_PPM_CORE
 #include <ppm/ppm.h>
 #endif
+#endif
 
 #include "cdi.h"
 #include "error.h"

tests/pio_write_setup_grid.c

@@ -13,7 +13,7 @@
 #endif
 #include "dmemory.h"
 
-#ifdef HAVE_PPM_CORE
+#if defined USE_MPI && defined HAVE_PPM_CORE
 #include <ppm/ppm_uniform_partition.h>
 #include <core/ppm_combinatorics.h>
 #endif

tests/simple_model_helper.c

@@ -9,7 +9,7 @@
 #include <stdlib.h>
 #include <string.h>
 
-#ifdef HAVE_PPM_CORE
+#if defined USE_MPI && defined HAVE_PPM_CORE
 #include <ppm/ppm_uniform_partition.h>
 #include <core/ppm_combinatorics.h>
 #endif
@@ -258,7 +258,7 @@ PPM_prime_factorization_32(uint32_t n, uint32_t **factors)
 
 #endif
 
-#ifndef HAVE_PPM_CORE
+#if !defined USE_MPI || !defined HAVE_PPM_CORE
 static char repeatable_rand_state[31 * sizeof(long)];
 
 long

tests/simple_model_helper.h

@@ -81,7 +81,7 @@ int PPM_prime_factorization_32(uint32_t n, uint32_t **factors);
 
 #endif
 
-#ifdef HAVE_PPM_CORE
+#if defined USE_MPI && defined HAVE_PPM_CORE
 #include <ppm/ppm.h>
 #include <core/ppm_random.h>
 #ifdef _OPENMP