gallium/dri: Switch xf86drm.h for util/libdrm.h to allow for the no-op shim to be used.

This patch allows MacOS to compile the dri[2] systems by switching from direct xf86drm.h to
the pre-existing util/libdrm.h.

Acked-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/28130>

src/egl/drivers/dri2/platform_surfaceless.c

@@ -29,7 +29,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
-#include <xf86drm.h>
+#include "util/libdrm.h"
 #include <sys/stat.h>
 #include <sys/types.h>
 

src/gallium/frontends/dri/dri2.c

@@ -28,7 +28,7 @@
  *    <wallbraker@gmail.com> Chia-I Wu <olv@lunarg.com>
  */
 
-#include <xf86drm.h>
+#include "util/libdrm.h"
 #include "git_sha1.h"
 #include "GL/mesa_glinterop.h"
 #include "GL/internal/mesa_interface.h"

src/glx/dri2.h

@@ -33,7 +33,7 @@
 #ifndef _DRI2_H_
 #define _DRI2_H_
 
-#include <xf86drm.h>
+#include "util/libdrm.h"
 #include <X11/extensions/Xfixes.h>
 #include <X11/extensions/dri2tokens.h>