Clarify error-handling by decreasing redundant symbols.

src/pio_util.c

@@ -112,25 +112,24 @@ void * pcdiXrealloc ( void *p, size_t size, const char *functionname,
 #ifdef USE_MPI
 void pcdiXMPI ( int iret, const char *filename, int line )
 {
-  char errorString1[MPI_MAX_ERROR_STRING + 1];
-  char errorString2[MPI_MAX_ERROR_STRING + 1];
+  char errorString[2][MPI_MAX_ERROR_STRING + 1];
   int len, errorClass, rank;
 
-  MPI_Comm_rank ( MPI_COMM_WORLD, &rank );
-
   if ( iret != MPI_SUCCESS )
     {
+      MPI_Comm_rank ( MPI_COMM_WORLD, &rank );
+
       MPI_Error_class ( iret, &errorClass );
-      MPI_Error_string ( errorClass, errorString1, &len );
-      errorString1[len] = '\0';
-      MPI_Error_string ( iret, errorString2, &len);
-      errorString2[len] = '\0';
+      MPI_Error_string ( errorClass, errorString[0], &len );
+      errorString[0][len] = '\0';
+      MPI_Error_string ( iret, errorString[1], &len);
+      errorString[1][len] = '\0';
 
       fprintf ( stderr, "MPI ERROR, pe%d, %s, line %d,"
                 "errorClass: \"%s\""
                 "errorString: \"%s\"\n",
                 rank, filename, line,
-                errorString1, errorString2);
+                errorString[0], errorString[1]);
 
       MPI_Abort ( MPI_COMM_WORLD, iret );
     }