misc/cgo/test: disable Test10303 for gccgo

When using gccgo it's OK if a pointer passed to C remains on the stack.
Gccgo does not have the clear distinction between C and Go stacks.

Change-Id: I3af9dd6fe078214ab16d9d8dad2d206608d7891d
Reviewed-on: https://go-review.googlesource.com/16774
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>

misc/cgo/test/issue10303.go

@@ -6,6 +6,8 @@
 
 package cgotest
 
+import "runtime"
+
 /*
 typedef int *intptr;
 
@@ -39,6 +41,10 @@ import (
 )
 
 func test10303(t *testing.T, n int) {
+	if runtime.Compiler == "gccgo" {
+		t.Skip("gccgo permits C pointers on the stack")
+	}
+
 	// Run at a few different stack depths just to avoid an unlucky pass
 	// due to variables ending up on different pages.
 	if n > 0 {