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

[Debarshi Ray <debarshir src gnome org>]

commit a2cb09d070cffcccf6089a392344b0252ef6f511
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.

 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())