Fixes trac:3486 - prevent opal_check_pmi from bleeding CPPFLAGS

This commit was SVN r28940.

The following Trac tickets were found above:
  Ticket 3486 --> https://svn.open-mpi.org/trac/ompi/ticket/3486

config/opal_check_pmi.m4

@@ -131,8 +131,8 @@ AC_DEFUN([OPAL_CHECK_PMI],[
                   $3])
            ])
 
-    # restore flags - have to add CPPFLAGS so base functions can find pmi.h
-    CPPFLAGS="$opal_check_pmi_$1_save_CPPFLAGS $opal_check_pmi_$1_CPPFLAGS"
+    # restore flags
+    CPPFLAGS="$opal_check_pmi_$1_save_CPPFLAGS"
     LDFLAGS="$opal_check_pmi_$1_save_LDFLAGS"
     LIBS="$opal_check_pmi_$1_save_LIBS"