GC controller input using named pipes

Currently only works on unix, but can be extended to other systems. Can
also be extended to do wiimotes.

Searches the Pipes folder for readable named pipes and creates a dolphin
input device out of them. Send controller inputs to the game by writing
to the file. Commands are described in Pipes.h.

Source/Core/InputCommon/ControllerInterface/ControllerInterface.h

@@ -38,6 +38,9 @@
 #if defined(HAVE_LIBEVDEV) && defined(HAVE_LIBUDEV)
 	#define CIFACE_USE_EVDEV
 #endif
+#if defined(USE_PIPES)
+	#define CIFACE_USE_PIPES
+#endif
 
 //
 // ControllerInterface