Revert "Properly handle old MPI libraries"

This reverts commit 144739bd.

configure.ac

@@ -92,16 +92,15 @@ if test "$enable_mpi" = "yes"; then
          *"Open MPI"*)
             MPI_THREAD_LIBS=""
             AC_MSG_RESULT([Open MPI])
-#            #  OpenMPI should be 1.8.6 or later, if not complain.
-#            #  Version is last word on first line of -version output.
-#            revision=`mpirun -version 2>&1 | grep "Open MPI" | awk '{print $NF}'`
-#            AX_COMPARE_VERSION( $revision, [ge], [1.8.6],,[good_mpi="no"] )
-#            if test "$good_mpi" = "no"; then
-#                AC_MSG_WARN([
-#    Open MPI version should be at least 1.8.6 (is $revision)])
-#                enable_mpi="yes (but with warning)"
-#		good_mpi="yes"
-#            fi
+            #  OpenMPI should be 1.8.6 or later, if not complain.
+            #  Version is last word on first line of -version output.
+            revision=`mpirun -version 2>&1 | grep "Open MPI" | awk '{print $NF}'`
+            AX_COMPARE_VERSION( $revision, [ge], [1.8.6],,[good_mpi="no"] )
+            if test "$good_mpi" = "no"; then
+                AC_MSG_WARN([
+    Open MPI version should be at least 1.8.6 (is $revision)])
+                enable_mpi="yes (but with warning)"
+            fi
          ;;
          *)
             MPI_THREAD_LIBS=""

src/version.c

@@ -134,16 +134,11 @@ const char *compiler_version(void) {
 const char *mpi_version(void) {
   static char version[256] = {0};
 #ifdef WITH_MPI
-  int len, std_version, std_subversion;
-#ifdef MPI_MAX_LIBRARY_VERSION_STRING
   static char lib_version[MPI_MAX_LIBRARY_VERSION_STRING] = {0};
-  MPI_Get_library_version(lib_version, &len);
-#else
-  static char lib_version[256] = {0};
-  sprintf(lib_version, "Unknow library");
-#endif
+  int len, std_version, std_subversion;
+  MPI_Get_library_lib_version(version, &len);
   MPI_Get_version(&std_version, &std_subversion);
-  sprintf(version, "%s (standard v %i.%i)", lib_version, std_version, std_subversion);
+  sprintf("%s (standard v %i.%i)", lib_version, std_version, std_subversion);
 #else
   sprintf(version, "Code was not compiled with MPI support");
 #endif