darwin: build fix
darwin: build fix

xfont.c:237:14: error: implicit declaration of function 'GetGLXDRIDrawable' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
   glxdraw = GetGLXDRIDrawable(CC->currentDpy, CC->currentDrawable);
             ^
Fixes regression from 291be28476ea60c6fb1eb2a882e2e25def5d3735

Signed-off-by: Jeremy Huddleston Sequoia <db3cec0cba09acb9cf8fd8bd399a3b27498cf883@apple.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler