support for GL_ARB_texture_non_power_of_two, patch from Eric Wasylishen.

git-svn-id: svn://svn.code.sf.net/p/quakespasm/code/trunk@931 af15c1b1-3010-417e-b628-4374ebc0bcbd
arch_def.h: update from uhexen2.

git-svn-id: svn://svn.code.sf.net/p/quakespasm/code/trunk@932 af15c1b1-3010-417e-b628-4374ebc0bcbd