FindMPI: Fix missing static warning in the mpi test source

Modules/FindMPI/test_mpi.c

@@ -7,15 +7,15 @@
 #endif
 
 #if defined(MPI_VERSION) && defined(MPI_SUBVERSION)
-const char mpiver_str[] = { 'I', 'N',
-                            'F', 'O',
-                            ':', 'M',
-                            'P', 'I',
-                            '-', 'V',
-                            'E', 'R',
-                            '[', ('0' + MPI_VERSION),
-                            '.', ('0' + MPI_SUBVERSION),
-                            ']', '\0' };
+const static char mpiver_str[] = { 'I', 'N',
+                                   'F', 'O',
+                                   ':', 'M',
+                                   'P', 'I',
+                                   '-', 'V',
+                                   'E', 'R',
+                                   '[', ('0' + MPI_VERSION),
+                                   '.', ('0' + MPI_SUBVERSION),
+                                   ']', '\0' };
 #endif
 
 int main(int argc, char* argv[])