Improve the error message a bit

This commit was SVN r27726.

config/orte_check_pmi.m4

@@ -67,7 +67,10 @@ AC_DEFUN([ORTE_CHECK_PMI],[
                                [orte_check_pmi_$1_CPPFLAGS="-I$with_pmi/include/slurm"],
                                [AC_MSG_RESULT([not found])
                                 AC_MSG_WARN([PMI support requested (via --with-pmi) but pmi.h])
-                                AC_MSG_WARN([not found under specified location $with_pmi])
+                                AC_MSG_WARN([not found under locations:])
+                                AC_MSG_WARN([    $with_pmi/include])
+                                AC_MSG_WARN([    $with_pmi/include/slurm])
+                                AC_MSG_WARN([Specified path: $with_pmi])
                                 AC_MSG_ERROR([Aborting])
                                 $3])])],
                  [AS_IF([test -f "/usr/include/slurm/pmi.h"],