fix various minor issues causing compilation failure with clang (#567)

- Include order and forward decls were breaking button.h because a
declared but not defined struct can't be initiated (honestly this file
was cooked, crazy include order).
- `MAXINT` is GCC specific, `INT_MAX` is portable.
- InterlockedDecrement takes a LONG, not ULONG
- an imgui printf-style call using a direct string instead of %s (let's
ignore the fact that it's actually safe based on how the str is
constructed)
- missing `override` on a virtual subclass
- `CALLBACK` on a lambda threw me for a loop, but I believe moving it
after the arg list is the correct approach (see if it builds on gcc I
guess)
- `std::result_of` was removed in C++20, which the project is built with

src/spice2x/cfg/button.h

@@ -1,15 +1,23 @@
 #pragma once
 
+#include <cstdint>
 #include <string>
 #include <utility>
 #include <vector>
 
-#include "api.h"
-
 namespace rawinput {
     class RawInputManager;
 }
 
+namespace GameAPI {
+    namespace Buttons {
+        enum State {
+            BUTTON_PRESSED = true,
+            BUTTON_NOT_PRESSED = false
+        };
+    }
+}
+
 enum ButtonAnalogType {
     BAT_NONE = 0,
     BAT_POSITIVE = 1,