[client] input: forward extended mouse buttons

Map the remaining Linux mouse buttons through Wayland and evdev.

Use one X11 translation for cooked and raw press and release events.

Ignore unsupported horizontal scrolling and extended SPICE buttons.

client/src/input_spice.c

@@ -59,11 +59,17 @@ static bool spiceMouseMotion(void * opaque, int32_t x, int32_t y)
 
 static bool spiceMousePress(void * opaque, unsigned int button)
 {
+  if (button > 7)
+    return true;
+
   return purespice_mousePress(button);
 }
 
 static bool spiceMouseRelease(void * opaque, unsigned int button)
 {
+  if (button > 7)
+    return true;
+
   return purespice_mouseRelease(button);
 }