[core, desktop] "fixes" from building on mxe/x86_64-w64-mingw32 (#396)

* well, i couldn't build the executable, but in anyway those build
  errors can come back later to bite our backs
* include missing include
* safeguard _MSC_VER only headers

* saw some of those changes on another PR but I cant find it at moment

Signed-off-by: Caio Oliveira <caiooliveirafarias0@gmail.com>

Reviewed-on: #396
Reviewed-by: crueter <crueter@eden-emu.dev>
Co-authored-by: Caio Oliveira <caiooliveirafarias0@gmail.com>
Co-committed-by: Caio Oliveira <caiooliveirafarias0@gmail.com>

src/yuzu/main.cpp

@@ -178,7 +178,9 @@ static FileSys::VirtualFile VfsDirectoryCreateFileWrapper(const FileSys::Virtual
 #include <QPlatformSurfaceEvent>
 #include <dwmapi.h>
 #include <windows.h>
+#ifdef _MSC_VER
 #pragma comment(lib, "Dwmapi.lib")
+#endif
 
 static inline void ApplyWindowsTitleBarDarkMode(HWND hwnd, bool enabled) {
     if (!hwnd)