common: Add module to get the current time zone.

src/common/time_zone.h

@@ -0,0 +1,17 @@
+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <string>
+
+namespace Common::TimeZone {
+
+/// Gets the default timezone, i.e. "GMT"
+std::string GetDefaultTimeZone();
+
+/// Gets the offset of the current timezone (from the default), in seconds
+int GetCurrentOffsetSeconds();
+
+} // namespace Common::TimeZone