Even more warning fixes

[Cyril Brulebois]

Hi again,

as promised, patches for SecurityLookupIDBy{Type,Class} this time. The
first patch ensures that the build doesn't break once the “take 2” of
SecurityLookupIDByType() removal is applied (3/4). I'll post an
alternative patch turning glxproxy.a into glxproxy.la, and adding an
explicit dependency on dix. Both seem to work fine enough for me.

Test-built, not test-run (I'm not running master yet, need to rebuild
some drivers for the input ABI bump).

Mraw,
KiBi.