Protect PMIx from bad configure entry

Ignore with-hwloc=internal or external as those are meaningless to pmix
(will upstream)

Signed-off-by: Ralph Castain <rhc@open-mpi.org>
(cherry picked from commit c498a7e77a)

opal/mca/pmix/pmix3x/pmix/config/pmix_setup_hwloc.m4

@@ -24,6 +24,8 @@ AC_DEFUN([PMIX_HWLOC_CONFIG],[
                                 [Search for hwloc libraries in DIR ])])
 
     pmix_hwloc_support=0
+    AS_IF([test "$with_hwloc" = "internal" || test "$with_hwloc" = "external"],
+          [with_hwloc=])
 
     if test "$with_hwloc" != "no"; then
         AC_MSG_CHECKING([for hwloc in])