dix: unexport ChangeGCXIDs()

Move non-exported gc functions to private header
No need to clutter public headers with non-exported stuff.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1365>

dix/dispatch.c

@@ -101,16 +101,17 @@ Equipment Corporation.
 #include <version-config.h>
 #endif
 
-#include "dix/dix_priv.h"
-#include "dix/registry_priv.h"
-#include "os/auth.h"
-
-#include "windowstr.h"
+#include <stddef.h>
 #include <X11/fonts/fontstruct.h>
 #include <X11/fonts/libxfont2.h>
 
+#include "dix/dix_priv.h"
+#include "dix/gc_priv.h"
+#include "dix/registry_priv.h"
 #include "dix/screenint_priv.h"
+#include "os/auth.h"
 
+#include "windowstr.h"
 #include "dixfontstr.h"
 #include "gcstruct.h"
 #include "selection.h"

dix/gc.c

@@ -48,9 +48,13 @@ SOFTWARE.
 #include <dix-config.h>
 #endif
 
+#include <assert.h>
 #include <X11/X.h>
 #include <X11/Xmd.h>
 #include <X11/Xproto.h>
+
+#include "dix/gc_priv.h"
+
 #include "misc.h"
 #include "resource.h"
 #include "gcstruct.h"
@@ -59,11 +63,9 @@ SOFTWARE.
 #include "scrnintstr.h"
 #include "region.h"
 #include "dixstruct.h"
-
 #include "privates.h"
 #include "dix.h"
 #include "xace.h"
-#include <assert.h>
 
 extern FontPtr defaultFont;
 

dix/gc_priv.h

@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: MIT OR X11
+ *
+ * Copyright © 2024 Enrico Weigelt, metux IT consult <info@metux.net>
+ * Copyright © 1987 by Digital Equipment Corporation, Maynard, Massachusetts.
+ * Copyright © 1987, 1998  The Open Group
+ */
+#ifndef _XSERVER_DIX_GC_PRIV_H
+#define _XSERVER_DIX_GC_PRIV_H
+
+#include "include/gc.h"
+
+int ChangeGCXIDs(ClientPtr client, GCPtr pGC, BITS32 mask, CARD32 * pval);
+
+#endif /* _XSERVER_DIX_GC_PRIV_H */

include/gc.h

@@ -83,11 +83,6 @@ typedef union {
     void *ptr;
 } ChangeGCVal, *ChangeGCValPtr;
 
-extern int ChangeGCXIDs(ClientPtr /*client */ ,
-                        GCPtr /*pGC */ ,
-                        BITS32 /*mask */ ,
-                        CARD32 * /*pval */ );
-
 extern _X_EXPORT int ChangeGC(ClientPtr /*client */ ,
                               GCPtr /*pGC */ ,
                               BITS32 /*mask */ ,