misc/cgo/testcshared: use correct install directory on windows

Updates #11058

Change-Id: I2a8bf4403b680ab8bf06fff18291f3bf67261e27
Reviewed-on: https://go-review.googlesource.com/69090Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>

misc/cgo/testcshared/cshared_test.go

@@ -42,15 +42,15 @@ func TestMain(m *testing.M) {
 
 	// Directory where cgo headers and outputs will be installed.
 	// The installation directory format varies depending on the platform.
-	installdir = path.Join("pkg", fmt.Sprintf("%s_%s_testcshared_shared", GOOS, GOARCH))
+	installdir = path.Join("pkg", fmt.Sprintf("%s_%s_testcshared", GOOS, GOARCH))
 	switch GOOS {
 	case "darwin":
 		libSuffix = "dylib"
-		installdir = path.Join("pkg", fmt.Sprintf("%s_%s_testcshared", GOOS, GOARCH))
 	case "windows":
 		libSuffix = "dll"
 	default:
 		libSuffix = "so"
+		installdir = path.Join("pkg", fmt.Sprintf("%s_%s_testcshared_shared", GOOS, GOARCH))
 	}
 
 	androiddir = fmt.Sprintf("/data/local/tmp/testcshared-%d", os.Getpid())