test: adjust issue4618 for gccgo allocation behaviour

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/41550044

test/fixedbugs/issue4618.go

@@ -9,6 +9,7 @@ package main
 import (
 	"fmt"
 	"os"
+	"runtime"
 	"testing"
 )
 
@@ -33,7 +34,7 @@ func main() {
 		fmt.Printf("AllocsPerRun(100, F) = %v, want 1\n", nf)
 		os.Exit(1)
 	}
-	if int(ng) != 0 {
+	if int(ng) != 0 && (runtime.Compiler != "gccgo" || int(ng) != 1) {
 		fmt.Printf("AllocsPerRun(100, G) = %v, want 0\n", ng)
 		os.Exit(1)
 	}