webdav: skip test that fails with gccgo

Change-Id: Ibcb2fbb6a016046dd67e92372376f0f639979e37
Reviewed-on: https://go-review.googlesource.com/24484
Reviewed-by: Mikio Hara <mikioh.mikioh@gmail.com>
Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

webdav/file_test.go

@@ -786,6 +786,9 @@ func TestMemFile(t *testing.T) {
 // memFile doesn't allocate a new buffer for each of those N times. Otherwise,
 // calling io.Copy(aMemFile, src) is likely to have quadratic complexity.
 func TestMemFileWriteAllocs(t *testing.T) {
+	if runtime.Compiler == "gccgo" {
+		t.Skip("gccgo allocates here")
+	}
 	fs := NewMemFS()
 	f, err := fs.OpenFile("/xxx", os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0666)
 	if err != nil {