Change mpx effective-target test into link test

	* lib/mpx-dg.exp (check_effective_target_mpx): Change into link test.
	Add main.

From-SVN: r218859

gcc/testsuite/ChangeLog

+2014-12-18  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
+
+	* lib/mpx-dg.exp (check_effective_target_mpx): Change into link test.
+	Add main.
+
 2014-12-18  Bin Cheng  <bin.cheng@arm.com>
 
 	PR tree-optimization/62178

gcc/testsuite/lib/mpx-dg.exp

@@ -18,7 +18,8 @@
 # error-free for trivial code, 0 otherwise.
 
 proc check_effective_target_mpx {} {
-    return [check_no_compiler_messages mpx object {
+    return [check_no_compiler_messages mpx executable {
 	int *foo (int *arg) { return arg; }
+	int main (void) { return foo ((void *)0) == 0; }
     } "-fcheck-pointer-bounds -mmpx"]
 }