Don't use -Wall with cgo. (stops compile warning)

door/input_windows.go

@@ -1,7 +1,9 @@
 package door
 
+// Don't use :  #cgo CFLAGS: -Wall
+// https://github.com/golang/go/issues/6883#issuecomment-383800123
+
 // #cgo LDFLAGS: -lws2_32
-// #cgo CFLAGS: -Wall
 // #include "input_windows.h"
 import "C"