[wing] meson: use fallback keyword of dependency for the subproject

[Ignacio Casal Quinteiro <icq src gnome org>]

commit 9eb6db5b1a42b0e5107fd858e4e1e08afcd73ef0
Author: Ignacio Casal Quinteiro <qignacio amazon com>
Date:   Wed Aug 22 13:14:22 2018 +0200

    meson: use fallback keyword of dependency for the subproject

 meson.build | 29 +++++------------------------
 1 file changed, 5 insertions(+), 24 deletions(-)
---
diff --git a/meson.build b/meson.build
index c694a43..7c9dcb7 100644
--- a/meson.build
+++ b/meson.build
@@ -120,30 +120,11 @@ core_inc = include_directories('.')
 # Required dependencies
 glib_req = '2.44.0'
 conf.set('GLIB_REQUIRED', glib_req)
-glib = dependency('glib-2.0', version: '>=' + glib_req, required: false)
-if not glib.found()
-  glib = subproject('glib').get_variable('libglib_dep')
-endif
-
-gobject = dependency('gobject-2.0', version: '>=' + glib_req, required: false)
-if not gobject.found()
-  gobject = subproject('glib').get_variable('libgobject_dep')
-endif
-
-gmodule = dependency('gmodule-2.0', version: '>=' + glib_req, required: false)
-if not gmodule.found()
-  gobject = subproject('glib').get_variable('libgmodule_dep')
-endif
-
-gio = dependency('gio-2.0', version: '>=' + glib_req, required: false)
-if not gio.found()
-  gio = subproject('glib').get_variable('libgio_dep')
-endif
-
-gio_windows = dependency('gio-windows-2.0', version: '>=' + glib_req, required: false)
-if not gio_windows.found()
-  gio_windows = subproject('glib').get_variable('libgiowin32_dep')
-endif
+glib = dependency('glib-2.0', version: '>=' + glib_req, fallback: ['glib', 'libglib_dep'])
+gobject = dependency('gobject-2.0', version: '>=' + glib_req, fallback: ['glib', 'libgobject_dep'])
+gmodule = dependency('gmodule-2.0', version: '>=' + glib_req, fallback: ['glib', 'libgmodule_dep'])
+gio = dependency('gio-2.0', version: '>=' + glib_req, fallback: ['glib', 'libgio_dep'])
+gio_windows = dependency('gio-windows-2.0', version: '>=' + glib_req, fallback: ['glib', 'libgiowin32_dep'])
 
 subdir('wing')
 subdir('tests')