Merge pull request open-mpi#1052 from jsquyres/pr/v2.0.0/fix-libfabric-user-intent

opal_check_libfabric: correctly check for user intent

Author: jsquyres

config/opal_check_libfabric.m4

@@ -74,7 +74,7 @@ AC_DEFUN([OPAL_CHECK_LIBFABRIC],[
 
     AS_IF([test $opal_check_libfabric_happy -eq 1],
           [$2],
-          [AS_IF([test "$opal_want_libfabric" = "yes"],
+          [AS_IF([test -n "$with_libfabric" && test "$with_libfabric" != "no"],
                  [AC_MSG_WARN([libfabric support requested (via --with-libfabric), but not found.])
                   AC_MSG_ERROR([Cannot continue.])])
            $3])