Fix glxWinCreateContext() function signature to align with commit 96d74138
"glx: Extend __GLXscreen::createContext to take attributes", which added more
parameters to the screen createContext function for implementing GLX_ARB_create_context
indirect.c: In function 'glxWinScreenProbe':
indirect.c:683:36: warning: assignment from incompatible pointer type
Signed-off-by: Jon TURNEY <jon.turney@dronecode.org.uk>
Reviewed-by: Colin Harrison <colin.harrison@virgin.net>