configure: Stop printing libxkbcommon in configure results

Cosmetic leftovers I missed when removing the configure
option to --disable-xkbcommon

Reviewed-by: Daniel Stone <daniels@collabora.com>
diff --git a/configure.ac b/configure.ac
index d8fe848..53faee3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -689,7 +689,6 @@
 
 	Cairo Renderer			${with_cairo}
 	EGL				${enable_egl}
-	libxkbcommon			${enable_xkbcommon}
 	xcb_xkb				${have_xcb_xkb}
 	XWayland			${enable_xwayland}
 	dbus				${enable_dbus}