[nautilus] meson: update submodule only if it doesn’t exist

[Ernestas Kulik <ernestask src gnome org>]

commit dc57c21448157c696bbe1315d2b7d7e5d3b9a180
Author: Ernestas Kulik <ernestask gnome org>
Date:   Sun Mar 5 21:49:17 2017 +0200

    meson: update submodule only if it doesn’t exist
    
    Some build servers don’t have git installed, which makes the tarball
    build fail when trying to update the libgd submodule. This commit adds a
    check for the existence of the root meson.build of libgd before running
    git.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=779603

 check_libgd.sh |    8 ++++++++
 meson.build    |    4 ++--
 2 files changed, 10 insertions(+), 2 deletions(-)
---
diff --git a/check_libgd.sh b/check_libgd.sh
new file mode 100755
index 0000000..f1fabc0
--- /dev/null
+++ b/check_libgd.sh
@@ -0,0 +1,8 @@
+#!/bin/sh
+
+if [ ! -f "${MESON_SOURCE_ROOT}/libgd/meson.build" ]
+then
+    git \
+        --git-dir="${MESON_SOURCE_ROOT}/.git" \
+        submodule update --init libgd
+fi
diff --git a/meson.build b/meson.build
index 8a6d659..13a92f6 100644
--- a/meson.build
+++ b/meson.build
@@ -102,8 +102,8 @@ nautilus_include_dirs = include_directories ('.')
 subdir ('eel')
 subdir ('libnautilus-extension')
 
-message ('Updating libgd submodule…')
-run_command ('git', '--git-dir="$MESON_SOURCE_ROOT/.git"', 'submodule', 'update', '--init', 'libgd')
+message ('Checking for libgd…')
+run_command ('check_libgd.sh')
 
 libgd_options = ['static=true',
                  'with-gtk-hacks=true',