Windows: Turn off TestBuildStopSignal

Signed-off-by: John Howard <jhoward@microsoft.com>

integration-cli/docker_cli_build_test.go

@@ -5662,6 +5662,7 @@ func (s *DockerSuite) TestBuildNullStringInAddCopyVolume(c *check.C) {
 }
 
 func (s *DockerSuite) TestBuildStopSignal(c *check.C) {
+	testRequires(c, DaemonIsLinux)
 	name := "test_build_stop_signal"
 	_, err := buildImage(name,
 		`FROM busybox