[grilo-plugins/sam/dummy-dep] build: Make it possible to use grilo-plugins as a Meson subproject

[Sam Thursfield <sthursfield src gnome org>]

commit 06e037f073b3a60322da8b15d70efc3c8fddd572
Author: Sam Thursfield <sam afuera me uk>
Date:   Sun Oct 6 21:04:48 2019 +0200

    build: Make it possible to use grilo-plugins as a Meson subproject
    
    This commit adds a dummy declare_dependency() object. This is needed
    so that other projects can embed grilo-plugins as a Meson subproject,
    like this:
    
        dependency('grilo-plugins-0.3', version: '>= 0.3.9',
                   fallback: ['grilo-plugins', 'grilo_plugins_dep']

 meson.build | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/meson.build b/meson.build
index f0fd5142..2c0cb779 100644
--- a/meson.build
+++ b/meson.build
@@ -176,3 +176,7 @@ subdir('src')
 subdir('help')
 subdir('po')
 subdir('tests')
+
+# This is a dummy dependency for use when grilo-plugins is built as a Meson
+# subproject.
+grilo_plugins_dep = declare_dependency()