runtime: do not run TestCgoSignalDeadlock on windows in short mode

The test takes up to 64 seconds on windows builders.
I've tried to reduce number of iterations in the test,
but it does not affect run time.
Fixes #6054.

R=golang-dev, alex.brainman
CC=golang-dev
https://golang.org/cl/12531043

src/pkg/runtime/crash_cgo_test.go

@@ -7,6 +7,7 @@
 package runtime_test
 
 import (
+	"runtime"
 	"testing"
 )
 
@@ -15,6 +16,9 @@ func TestCgoCrashHandler(t *testing.T) {
 }
 
 func TestCgoSignalDeadlock(t *testing.T) {
+	if testing.Short() && runtime.GOOS == "windows" {
+		t.Skip("Skipping in short mode") // takes up to 64 seconds
+	}
 	got := executeTest(t, cgoSignalDeadlockSource, nil)
 	want := "OK\n"
 	if got != want {