mi: drop using HAVE_DIX_CONFIG_H

This symbol is always defined, and the header is always present,
so no need to check for it.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>

mi/miinitext.h

@@ -70,14 +70,11 @@ SOFTWARE.
  * the sale, use or other dealings in this Software without prior written
  * authorization from the copyright holder(s) and author(s).
  */
-
-#ifdef HAVE_DIX_CONFIG_H
-#include <dix-config.h>
-#endif
-
 #ifndef MIINITEXT_H
 #define MIINITEXT_H
 
+#include <dix-config.h>
+
 void ListStaticExtensions(void);
 
 #endif /* MIINITEXT_H */

mi/mioverlay.h

@@ -1,11 +1,8 @@
-
-#ifdef HAVE_DIX_CONFIG_H
-#include <dix-config.h>
-#endif
-
 #ifndef __MIOVERLAY_H
 #define __MIOVERLAY_H
 
+#include <dix-config.h>
+
 typedef void (*miOverlayTransFunc) (ScreenPtr, int, BoxPtr);
 typedef Bool (*miOverlayInOverlayFunc) (WindowPtr);
 

mi/miscanfill.h

@@ -25,13 +25,11 @@ other dealings in this Software without prior written authorization
 from The Open Group.
 
 */
-
-#ifdef HAVE_DIX_CONFIG_H
-#include <dix-config.h>
-#endif
-
 #ifndef SCANFILLINCLUDED
 #define SCANFILLINCLUDED
+
+#include <dix-config.h>
+
 /*
  *     scanfill.h
  *

mi/mivalidate.h

@@ -25,14 +25,11 @@ other dealings in this Software without prior written authorization
 from The Open Group.
 
 */
-
-#ifdef HAVE_DIX_CONFIG_H
-#include <dix-config.h>
-#endif
-
 #ifndef MIVALIDATE_H
 #define MIVALIDATE_H
 
+#include <dix-config.h>
+
 #include "regionstr.h"
 
 typedef union _Validate {