Fix includes right throughout the Xserver tree:

change "foo.h" to <X11/foo.h> for core headers, e.g. X.h, Xpoll.h;
change "foo.h", "extensions/foo.h" and "X11/foo.h" to
    <X11/extensions/foo.h> for extension headers, e.g. Xv.h;
change "foo.[ch]" to <X11/Xtrans/foo.[ch]> for Xtrans files.

hw/dmx/dmxinit.c

@@ -54,7 +54,7 @@
 #include "dmxpict.h"
 #endif
 
-#include "Xos.h"                /* For gettimeofday */
+#include <X11/Xos.h>                /* For gettimeofday */
 #include "dixstruct.h"
 #include "panoramiXsrv.h"
 
@@ -64,8 +64,8 @@
 #include <GL/glx.h>
 #include <GL/glxint.h>
 #include "dmx_glxvisuals.h"
-#include "Xext.h"
-#include "extutil.h"
+#include <X11/extensions/Xext.h>
+#include <X11/extensions/extutil.h>
 
 extern void GlxSetVisualConfigs(
     int               nconfigs,