meson: Allow to process multiple wayland protocols

src/meson.build

@@ -14,8 +14,14 @@ phosh_resources = gnome.compile_resources(
 )
 
 
-shell_proto_header = gen_scanner_client_header.process('../protocol/phosh-mobile-shell.xml')
-shell_proto_code = gen_scanner_client_code.process('../protocol/phosh-mobile-shell.xml')
+wl_protos = [
+  'phosh-mobile-shell.xml',
+]
+wl_proto_deps = []
+foreach proto: wl_protos
+  wl_proto_deps += gen_scanner_client_header.process('../protocol/' + proto)
+  wl_proto_deps += gen_scanner_client_code.process('../protocol/' + proto)
+endforeach
 
 phosh_sources = [
   'background.c',
@@ -32,10 +38,8 @@ phosh_sources = [
   'settings.c',
   'settings.h',
   'settings/brightness.c',
-  shell_proto_header,
-  shell_proto_code,
   phosh_resources,
-]
+] + wl_proto_deps
 
 phosh_deps = [
   dependency('gnome-desktop-3.0'),