CMakeLists: Ensure we specify Unicode as the codepage on Windows

Previously we were building with MBCS, which is pretty undesirable. We
want the application to be Unicode-aware in general.

Currently, we make the command line variant of yuzu use ANSI variants of
the non-standard getopt functions that we link in for Windows, given we
only have an ANSI option-set.

We should really replace getopt with a library that we make all build
types of yuzu link in, but this will have to do for the time being.

src/dedicated_room/citra-room.cpp

@@ -11,13 +11,6 @@
 #include <thread>
 #include <glad/glad.h>
 
-#ifdef _MSC_VER
-#include <getopt.h>
-#else
-#include <getopt.h>
-#include <unistd.h>
-#endif
-
 #ifdef _WIN32
 // windows.h needs to be included before shellapi.h
 #include <windows.h>
@@ -40,6 +33,12 @@
 #include "web_service/verify_user_jwt.h"
 #endif
 
+#undef _UNICODE
+#include <getopt.h>
+#ifndef _MSC_VER
+#include <unistd.h>
+#endif
+
 static void PrintHelp(const char* argv0) {
     std::cout << "Usage: " << argv0
               << " [options] <filename>\n"