Input: remove unused stuff & clean up

1. removed zl, zr and c-stick from HID::PadState. They are handled by IR, not HID
2. removed button handling in EmuWindow
3. removed key_map
4. cleanup #include

src/video_core/renderer_opengl/gl_rasterizer_cache.cpp

@@ -17,6 +17,7 @@
 #include "common/vector_math.h"
 #include "core/frontend/emu_window.h"
 #include "core/memory.h"
+#include "core/settings.h"
 #include "video_core/pica_state.h"
 #include "video_core/renderer_opengl/gl_rasterizer_cache.h"
 #include "video_core/renderer_opengl/gl_state.h"