xkb: add a cause to the xkb indicator update after a keymap change

Regression introduce by ac164e5887 which calls
XkbUpdateAllDeviceIndicators() with two NULL arguments. A few layers down into
the stack and we triggered a NULL-pointer dereference. In theory a NULL cause
is acceptable since we don't actually change modifier state here. Instead of
updating all places to check for NULL just set the cause to the client
request and go to the pub.

https://bugs.freedesktop.org/show_bug.cgi?id=96384

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Julien Cristau <jcristau@debian.org>
Reviewed-by: Daniel Stone <daniels@collabora.com>

xkb/xkb.c

@@ -5706,6 +5706,7 @@ ProcXkbGetKbdByName(ClientPtr client)
     xkbGetGeometryReply grep = { 0 };
     XkbComponentNamesRec names = { 0 };
     XkbDescPtr xkb, new;
+    XkbEventCauseRec cause;
     unsigned char *str;
     char mapFile[PATH_MAX];
     unsigned len;
@@ -6016,7 +6017,8 @@ ProcXkbGetKbdByName(ClientPtr client)
         new = NULL;
     }
     XkbFreeComponentNames(&names, FALSE);
-    XkbUpdateAllDeviceIndicators(NULL, NULL);
+    XkbSetCauseXkbReq(&cause, X_kbGetKbdByName, client);
+    XkbUpdateAllDeviceIndicators(NULL, &cause);
 
     return Success;
 }