Add command line parsing to UICommon.

Source/Core/UICommon/CommandLineParse.h

@@ -0,0 +1,23 @@
+// Copyright 2017 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#include <memory>
+
+namespace optparse
+{
+class OptionParser;
+class Values;
+}
+
+namespace CommandLineParse
+{
+enum class ParserOptions
+{
+  IncludeGUIOptions,
+  OmitGUIOptions,
+};
+
+std::unique_ptr<optparse::OptionParser> CreateParser(ParserOptions options);
+optparse::Values& ParseArguments(optparse::OptionParser* parser, int argc, char** argv);
+}