games/gzdoom: fix runtime against SDL newer than 2.0

The game was supposed to be restricted to newer versions of SDL than
2.0.6, but they inadvertently only checked the patch number of the
current SDL version. The provided patch is pulled from a later version
of GZDoom and uses the correct SDL version check macro.

(cherry picked from commit 32b4b09f7dbf1b1e32ffb844a15f7e842e5cda2a)