Xext: geext: move struct _GEExtension into geext.c

Not used anywhere outside geext implementation itself,
so shouldn't be public at all.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1811>
(cherry picked from commit a7600ac884)

Xext/geext.c

@@ -36,6 +36,12 @@
 
 DevPrivateKeyRec GEClientPrivateKeyRec;
 
+/** Struct to keep information about registered extensions */
+typedef struct _GEExtension {
+    /** Event swapping routine */
+    void (*evswap) (xGenericEvent *from, xGenericEvent *to);
+} GEExtension, *GEExtensionPtr;
+
 static GEExtension GEExtensions[MAXEXTENSIONS];
 
 /* Major available requests */

Xext/geext.h

@@ -34,12 +34,6 @@ from the author.
 #define _GEEXT_H_
 #include <X11/extensions/geproto.h>
 
-/** Struct to keep information about registered extensions */
-typedef struct _GEExtension {
-    /** Event swapping routine */
-    void (*evswap) (xGenericEvent *from, xGenericEvent *to);
-} GEExtension, *GEExtensionPtr;
-
 /* Interface for other extensions */
 extern _X_EXPORT void GERegisterExtension(int extension,
                                           void (*ev_dispatch) (xGenericEvent