Set console codepage to utf-8 (on Windows), and restore old one on exit

Avoid mojibake.

src/common.cpp

@@ -65,6 +65,20 @@ template <typename T> struct TypeIs64BitInteger { enum {value = false}; };
 template <> struct TypeIs64BitInteger<u64> { enum {value = true}; };
 template <> struct TypeIs64BitInteger<i64> { enum {value = true}; };
 
+#if defined(GB_SYSTEM_WINDOWS)
+uint32_t old_console_codepage = 0;
+void set_utf8_codepage() {
+	old_console_codepage = GetConsoleOutputCP();
+}
+
+void restore_old_codepage() {
+	// Nothing we can do if this fails, so we're not asserting or anything.
+	SetConsoleOutputCP(old_console_codepage);
+}
+#else
+void set_utf8_codepage() {}
+void restore_old_codepage() {}
+#endif
 
 
 #include "unicode.cpp"