#551 [Patch] SDL2 throws out some input in relative mouse mode

[cream]

ezquake 3.0 is throwing out mouse input when SDL2 is set to use relative coordinates (via in_raw 1). The problem is that mx and my are being reset regardless of the mouse coordinate mode whenever the input is processed.

This patch does the following:

1.) Simplifies the code by making both input styles (raw and processed) use relative coordinates. SDL2 has a hint for this, so there's no longer any need to warp the cursor manually.

2.) Removes the offending line of code causing this bug in in_sdl2.c, which is safe since all input is now using relative coordinates.

[meag]

Closing: duplicate of github pull request https://github.com/ezQuake/ezquake-source/pull/28