[gnome-photos/wip/rishi/meson-submodules] build: Ensure that the Git submodules are kept updated

[Debarshi Ray <debarshir src gnome org>]

commit dc00c69b62d4cdf7c0d62dd447d3a91d80f4c12f
Author: Debarshi Ray <debarshir gnome org>
Date:   Tue Sep 25 07:56:38 2018 +0200

    build: Ensure that the Git submodules are kept updated
    
    It's assumed that those building release tarballs, like distributions,
    might not have Git in their buildroots. Therefore, this is skipped for
    'plain' builds.
    
    https://gitlab.gnome.org/GNOME/gnome-photos/merge_requests/59

 meson.build | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index 80892311..e9040dba 100644
--- a/meson.build
+++ b/meson.build
@@ -29,6 +29,11 @@ po_dir = join_paths(source_root, 'po')
 
 top_inc = include_directories('.')
 
+git = find_program('git')
+if not photos_buildtype.contains('plain')
+  run_command(git, '-C', source_root, 'submodule', 'update', '--init', '--recursive')
+endif
+
 cc = meson.get_compiler('c')
 
 config_h = configuration_data()
@@ -37,7 +42,6 @@ config_h.set_quoted('PACKAGE_TARNAME', meson.project_name())
 config_h.set_quoted('PACKAGE_URL', 'https://wiki.gnome.org/Apps/Photos')
 config_h.set_quoted('PACKAGE_VERSION', meson.project_version())
 
-git = find_program('git')
 res = run_command(git, '-C', source_root, 'describe')
 if res.returncode() == 0
   config_h.set_quoted('PACKAGE_COMMIT_ID', res.stdout().strip())