xext: move include guards up to wrap the whole file

See: https://gcc.gnu.org/onlinedocs/cppinternals/Guard-Macros.html
Signed-off-by: Mike Gelfand <mikedld@mikedld.com>

Xext/dpmsproc.h

@@ -1,10 +1,10 @@
 /* Prototypes for functions that the DDX must provide */
 
-#include <dix-config.h>
-
 #ifndef _DPMSPROC_H_
 #define _DPMSPROC_H_
 
+#include <dix-config.h>
+
 #include "dixstruct.h"
 
 extern int DPMSSet(ClientPtr client, int level);

Xext/panoramiX.h

@@ -28,15 +28,11 @@ Equipment Corporation.
 
 /* THIS IS NOT AN X PROJECT TEAM SPECIFICATION */
 
-/*
- *	PanoramiX definitions
- */
-
-#include <dix-config.h>
-
 #ifndef _PANORAMIX_H_
 #define _PANORAMIX_H_
 
+#include <dix-config.h>
+
 #include <X11/Xmd.h>
 #include <X11/extensions/panoramiXproto.h>
 
@@ -45,6 +41,10 @@ Equipment Corporation.
 #include "gcstruct.h"
 #include "dixstruct.h"
 
+/*
+ *	PanoramiX definitions
+ */
+
 typedef struct _PanoramiXInfo {
     XID id;
 } PanoramiXInfo;

Xext/panoramiXsrv.h

@@ -1,9 +1,8 @@
-
-#include <dix-config.h>
-
 #ifndef _PANORAMIXSRV_H_
 #define _PANORAMIXSRV_H_
 
+#include <dix-config.h>
+
 #include "panoramiX.h"
 
 extern int PanoramiXNumScreens;

Xext/sleepuntil.h

@@ -24,11 +24,11 @@
  * XFree86 Project.
  */
 
-#include <dix-config.h>
-
 #ifndef _SLEEPUNTIL_H_
 #define _SLEEPUNTIL_H_ 1
 
+#include <dix-config.h>
+
 #include "dix.h"
 
 extern int ClientSleepUntil(ClientPtr client,