[four-in-a-row] Add --version command-line support.

[Arnaud B. <arnaudb src gnome org>]

commit 49f2381d30e03a679faa93d054abc1b946ba0138
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Thu Dec 26 22:09:13 2019 +0100

    Add --version command-line support.

 meson.build            | 13 ++++++++-----
 src/four-in-a-row.vala | 22 ++++++++++++++++++++++
 src/meson.build        |  1 +
 3 files changed, 31 insertions(+), 5 deletions(-)
---
diff --git a/meson.build b/meson.build
index cb03e1c..c118943 100644
--- a/meson.build
+++ b/meson.build
@@ -15,11 +15,14 @@ python3 = import('python3')
 
 application_id = 'org.gnome.Four-in-a-row'
 
-gio_dependency = dependency('gio-2.0', version: '>= 2.40.0')
-glib_dependency = dependency('glib-2.0', version: '>= 2.40.0')
-gsound_dependency = dependency('gsound', version: '>= 1.0.2')
-gtk_dependency = dependency('gtk+-3.0', version: '>= 3.13.2')
-rsvg_dependency = dependency('librsvg-2.0', version: '>= 2.32.0')
+valac = meson.get_compiler('vala')
+
+gio_dependency      = dependency('gio-2.0',     version: '>= 2.40.0')
+glib_dependency     = dependency('glib-2.0',    version: '>= 2.40.0')
+gsound_dependency   = dependency('gsound',      version: '>= 1.0.2')
+gtk_dependency      = dependency('gtk+-3.0',    version: '>= 3.13.2')
+posix_dependency    = valac.find_library('posix')
+rsvg_dependency     = dependency('librsvg-2.0', version: '>= 2.32.0')
 
 appstream_util          = find_program('appstream-util',        required: false)
 desktop_file_validate   = find_program('desktop-file-validate', required: false)
diff --git a/src/four-in-a-row.vala b/src/four-in-a-row.vala
index d0ae0e4..c16ad2d 100644
--- a/src/four-in-a-row.vala
+++ b/src/four-in-a-row.vala
@@ -89,6 +89,13 @@ private class FourInARow : Gtk.Application
     [CCode (notify = false)] internal bool  sound_on        { private get; internal set; }
     private uint8 theme_id;
 
+    private const OptionEntry [] option_entries =
+    {
+        /* Translators: command-line option description, see 'four-in-a-row --help' */
+        { "version", 'v', OptionFlags.NONE, OptionArg.NONE, null, N_("Print release version and exit"), null 
},
+        {}
+    };
+
     private const GLib.ActionEntry app_entries [] =  // see also add_actions()
     {
         { "game-type",      null,           "s", "'dark'", change_game_type },
@@ -121,6 +128,21 @@ private class FourInARow : Gtk.Application
     private FourInARow ()
     {
         Object (application_id: "org.gnome.Four-in-a-row", flags: ApplicationFlags.FLAGS_NONE);
+
+        add_main_option_entries (option_entries);
+    }
+
+    protected override int handle_local_options (GLib.VariantDict options)
+    {
+        if (options.contains ("version"))
+        {
+            /* NOTE: Is not translated so can be easily parsed */
+            stdout.printf ("%1$s %2$s\n", "four-in-a-row", VERSION);
+            return Posix.EXIT_SUCCESS;
+        }
+
+        /* Activate */
+        return -1;
     }
 
     protected override void startup ()
diff --git a/src/meson.build b/src/meson.build
index ddf22aa..f0084ca 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -41,6 +41,7 @@ executable(
         glib_dependency,
         gsound_dependency,
         gtk_dependency,
+        posix_dependency,
         rsvg_dependency
     ],
     c_args: [