meson: track proto sources dependency on wayland-client

libwayland maybe installed outside of default C preprocessor search.

libclient_protos.a.p/idle-inhibit-unstable-v1-protocol.c:28:10: fatal error: 'wayland-util.h' file not found
 #include "wayland-util.h"
          ^~~~~~~~~~~~~~~~

meson.build

@@ -29,6 +29,7 @@ client_protos_headers = wayland_scanner_client.process(xml)
 lib_client_protos = static_library(
   'client_protos',
   [ client_protos_src, client_protos_headers ],
+  dependencies: [ wayland_client ],
 )
 
 client_protos = declare_dependency(