Backends/Internals: Don't use IME and clipboard default win32 functions when WINAPI_FAMILY_GAMES (#7585)

imgui.cpp

@@ -1000,7 +1000,8 @@ CODE
 #else
 #include <windows.h>
 #endif
-#if defined(WINAPI_FAMILY) && (WINAPI_FAMILY == WINAPI_FAMILY_APP) // UWP doesn't have all Win32 functions
+#if defined(WINAPI_FAMILY) && (WINAPI_FAMILY == WINAPI_FAMILY_APP || WINAPI_FAMILY == WINAPI_FAMILY_GAMES)
+// The UWP and GDK Win32 API subsets don't support clipboard nor IME functions
 #define IMGUI_DISABLE_WIN32_DEFAULT_CLIPBOARD_FUNCTIONS
 #define IMGUI_DISABLE_WIN32_DEFAULT_IME_FUNCTIONS
 #endif