Fixed MinGW builds uses UTF-8 friendly _wfopen(). (#8300)

Amend bbd0a37bd, 40db2ca09

docs/CHANGELOG.txt

@@ -67,6 +67,7 @@ Other changes:
   created from a single comma character, affecting some fonts/settings (not all).
 - Demo: Added label edition to Property Editor demo + fix an ID issue. (#8266) [@moritz-h]
 - Misc: Fixed misc/cpp/imgui_stdlib.h/.cpp not supporting IMGUI_DISABLE. (#8294) [@juur]
+- Misc: Fixed MinGW builds uses UTF-8 friendly _wfopen(). (#8300)
 - Backends: Allegro5: Avoid calling al_set_mouse_cursor() repeatedly since it appears
   to leak on on X11 (#8256). [@Helodity]
 - Backends: Metal: Fixed leaks when using metal-cpp. (#8276, #8166) [@selimsandal]

imgui.cpp

@@ -2282,7 +2282,7 @@ ImGuiID ImHashStr(const char* data_p, size_t data_size, ImGuiID seed)
 
 ImFileHandle ImFileOpen(const char* filename, const char* mode)
 {
-#if defined(_WIN32) && !defined(IMGUI_DISABLE_WIN32_FUNCTIONS) && !defined(__CYGWIN__) && !defined(__GNUC__)
+#if defined(_WIN32) && !defined(IMGUI_DISABLE_WIN32_FUNCTIONS) && (defined(__MINGW32__) || (!defined(__CYGWIN__) && !defined(__GNUC__)))
     // We need a fopen() wrapper because MSVC/Windows fopen doesn't handle UTF-8 filenames.
     // Previously we used ImTextCountCharsFromUtf8/ImTextStrFromUtf8 here but we now need to support ImWchar16 and ImWchar32!
     const int filename_wsize = ::MultiByteToWideChar(CP_UTF8, 0, filename, -1, NULL, 0);