Rename GtkActionMuxer's private header

Follow the naming policy for private headers.

gtk/gtkactionmuxer.c

@@ -19,7 +19,7 @@
 
 #include "config.h"
 
-#include "gtkactionmuxer.h"
+#include "gtkactionmuxerprivate.h"
 
 #include "gtkactionobservable.h"
 #include "gtkactionobserver.h"

gtk/gtkapplicationaccels.c

@@ -20,9 +20,11 @@
  */
 
 #include "config.h"
+
 #include "gtkapplicationaccelsprivate.h"
+#include "gtkactionmuxerprivate.h"
+
 #include <string.h>
-#include "gtkactionmuxer.h"
 
 typedef struct
 {

gtk/gtkapplicationprivate.h

@@ -24,7 +24,7 @@
 #include "gtkapplicationwindow.h"
 #include "gtkwindowprivate.h"
 
-#include "gtkactionmuxer.h"
+#include "gtkactionmuxerprivate.h"
 #include "gtkapplicationaccelsprivate.h"
 
 G_BEGIN_DECLS

gtk/gtkmenutrackeritem.c

@@ -20,12 +20,10 @@
 #include "config.h"
 
 #include "gtkmenutrackeritem.h"
-#include "gtkactionmuxer.h"
+#include "gtkactionmuxerprivate.h"
 #include "gtkdebug.h"
 #include "gtkintl.h"
 
-#include "gtkactionmuxer.h"
-
 #include <string.h>
 
 /*< private >

gtk/gtkpopover.c

@@ -121,7 +121,7 @@
 #include "gtkseparator.h"
 #include "gtkmodelbutton.h"
 #include "gtkwidgetprivate.h"
-#include "gtkactionmuxer.h"
+#include "gtkactionmuxerprivate.h"
 #include "gtkmenutracker.h"
 #include "gtkstack.h"
 #include "gtksizegroup.h"

gtk/gtkwidgetprivate.h

@@ -29,7 +29,7 @@
 #include "gtkwidget.h"
 #include "gtkcontainer.h"
 #include "gtkeventcontroller.h"
-#include "gtkactionmuxer.h"
+#include "gtkactionmuxerprivate.h"
 #include "gtksizerequestcacheprivate.h"
 
 G_BEGIN_DECLS