Tweak the MH dynamic lighting speedup to be more correct: upload the lightmaps from the current frame instead of the previous frame.

It was possible, but unlikely, to see artifacts from the previous code in some circumstances, e.g. "host_maxfps 10" and spin around quickly near a flashing light e1m1, you may see a surface drawn with an out-of-date lightmap for one frame.

git-svn-id: svn+ssh://svn.code.sf.net/p/quakespasm/code/trunk@1130 af15c1b1-3010-417e-b628-4374ebc0bcbd