[fix] Uncomment accidentally commented out SDL_TOUCH_MOUSEID check in SDL2_0.lua (#1607)

Presumably fairly harmless except in wasted processing because for motion the two are identical or close to it regardless.

Noticed in koreader/koreader#10417 (comment)

Author: Frenzie

ffi/SDL2_0.lua

@@ -366,7 +366,7 @@ function S.waitForEvent(sec, usec)
         genEmuEvent(C.EV_KEY, event.key.keysym.sym, 0)
     elseif event.type == SDL.SDL_TEXTINPUT then
         genEmuEvent(C.EV_SDL, SDL.SDL_TEXTINPUT, ffi.string(event.text.text))
-    elseif event.type == SDL.SDL_MOUSEMOTION --and event.motion.which ~= SDL_TOUCH_MOUSEID
+    elseif event.type == SDL.SDL_MOUSEMOTION and event.motion.which ~= SDL_TOUCH_MOUSEID
         or event.type == SDL.SDL_FINGERMOTION then
         local is_finger = event.type == SDL.SDL_FINGERMOTION
         local slot