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/yuzu_cmd/yuzu.cpp

@@ -32,11 +32,7 @@
 #include "yuzu_cmd/config.h"
 #include "yuzu_cmd/emu_window/emu_window_sdl2.h"
 
-#include <getopt.h>
 #include "core/file_sys/registered_cache.h"
-#ifndef _MSC_VER
-#include <unistd.h>
-#endif
 
 #ifdef _WIN32
 // windows.h needs to be included before shellapi.h
@@ -45,6 +41,12 @@
 #include <shellapi.h>
 #endif
 
+#undef _UNICODE
+#include <getopt.h>
+#ifndef _MSC_VER
+#include <unistd.h>
+#endif
+
 #ifdef _WIN32
 extern "C" {
 // tells Nvidia and AMD drivers to use the dedicated GPU by default on laptops with switchable