meson: Improve gdbus-codegen custom target dependencies

Ensure that the custom targets that use gdbus-codegen get rebuilt when
any of the gdbus-codegen files are changed.

https://bugzilla.gnome.org/show_bug.cgi?id=752239

gio/gdbus-2.0/codegen/meson.build

@@ -23,19 +23,19 @@ gdbus_codegen = configure_file(input : 'gdbus-codegen.in',
 
 codegen_dir = join_paths(get_option('datadir'), 'glib-2.0/codegen')
 
-configure_file(input : 'config.py.in',
-  output : 'config.py',
-  install : true,
-  install_dir : codegen_dir,
-  configuration : gdbus_codegen_conf
-)
+gdbus_codegen_built_files = []
+gdbus_codegen_built_files += configure_file(input : 'config.py.in',
+                                            output : 'config.py',
+                                            install : true,
+                                            install_dir : codegen_dir,
+                                            configuration : gdbus_codegen_conf)
 
 blank_conf = configuration_data()
 foreach f : gdbus_codegen_files
   # Copy these into the builddir so that gdbus-codegen can be used uninstalled
   # and then install it too so that it can be used after installation
-  configure_file(input : f, output : f,
-    install : true,
-    install_dir : codegen_dir,
-    configuration : blank_conf)
+  gdbus_codegen_built_files += configure_file(input : f, output : f,
+                                              install : true,
+                                              install_dir : codegen_dir,
+                                              configuration : blank_conf)
 endforeach

gio/meson.build

@@ -174,6 +174,7 @@ xdp_dbus_generated = custom_target('xdp-dbus',
              'org.freedesktop.portal.NetworkMonitor.xml',
              'org.freedesktop.portal.ProxyResolver.xml'],
     output : ['xdp-dbus.h', 'xdp-dbus.c'],
+    depend_files : gdbus_codegen_built_files,
     command : [python, gdbus_codegen,
                '--interface-prefix', 'org.freedesktop.portal.',
                '--output-directory', '@OUTDIR@',
@@ -193,6 +194,7 @@ xdp_dbus_generated = custom_target('xdp-dbus',
 gdbus_daemon_generated = custom_target('gdbus-daemon-generated',
     input : ['dbus-daemon.xml'],
     output : ['gdbus-daemon-generated.h', 'gdbus-daemon-generated.c'],
+    depend_files : gdbus_codegen_built_files,
     command : [python, gdbus_codegen,
                '--interface-prefix', 'org.',
                '--output-directory', '@OUTDIR@',

gio/tests/meson.build

@@ -146,6 +146,7 @@ if host_machine.system() != 'windows'
         input :   ['test-codegen.xml'],
         output :  ['gdbus-test-codegen-generated.h',
                    'gdbus-test-codegen-generated.c'],
+        depend_files : gdbus_codegen_built_files,
         command : [python, gdbus_codegen,
                    '--interface-prefix', 'org.project.',
                    '--output-directory', '@OUTDIR@',