misc/cgo/test: skip Setgid test on Android

The setgid syscall is blocked on Android in app context.

Change-Id: I1ff25840bbc25d472ad4e29eb1b51f183a6c4392
Reviewed-on: https://go-review.googlesource.com/c/go/+/170949
Run-TryBot: Elias Naur <mail@eliasnaur.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

misc/cgo/test/cgo_linux_test.go

@@ -4,8 +4,16 @@
 
 package cgotest
 
-import "testing"
+import (
+	"runtime"
+	"testing"
+)
 
-func TestSetgid(t *testing.T)  { testSetgid(t) }
+func TestSetgid(t *testing.T) {
+	if runtime.GOOS == "android" {
+		t.Skip("unsupported on Android")
+	}
+	testSetgid(t)
+}
 func Test6997(t *testing.T)    { test6997(t) }
 func TestBuildID(t *testing.T) { testBuildID(t) }