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/overlay/windows/config.cpp

@@ -3182,7 +3182,7 @@ namespace overlay::windows {
         } else if (filter != nullptr) {
             cat = "Search results";
         }
-        ImGui::TextColored(ImVec4(1.f, 0.7f, 0, 1), cat.c_str());
+        ImGui::TextColored(ImVec4(1.f, 0.7f, 0, 1), "%s", cat.c_str());
         ImGui::Separator();
 
         // render table