Revert "glx/dri2: Disable AIGLX if indirect GLX is disabled"

This reverts commit d61ae18074.

If the DRI2 provider is disabled, then we don't advertise the correct
GLX extensions to clients, and things like GLES fail.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90442
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>

glx/glxdri2.c

@@ -936,9 +936,6 @@ __glXDRIscreenProbe(ScreenPtr pScreen)
     size_t buffer_size;
     ScrnInfoPtr pScrn = xf86ScreenToScrn(pScreen);
 
-    if (!enableIndirectGLX)
-	    return NULL;
-
     screen = calloc(1, sizeof *screen);
     if (screen == NULL)
         return NULL;