[gnome-shell] build: Fix git submodule fetching with builddir != srcdir

[Bastien Nocera <hadess src gnome org>]

commit 56d0d7253bfab7476720a231cf6f2554ef92e256
Author: Bastien Nocera <hadess hadess net>
Date:   Mon Oct 17 13:50:08 2016 +0200

    build: Fix git submodule fetching with builddir != srcdir
    
    We were running the git submodule update in builddir, instead of srcdir,
    which might have lead to submodules not updating, and submodule tags
    being reverted to older versions in some contributions.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=773085

 autogen.sh |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/autogen.sh b/autogen.sh
index 492e5d0..3ab889e 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -11,6 +11,8 @@ test -z "$srcdir" && srcdir=.
     exit 1
 }
 
+pushd $srcdir
+
 # Fetch submodules if needed
 if test ! -f src/gvc/Makefile.am || test ! -f data/theme/gnome-shell-sass/COPYING;
 then
@@ -19,6 +21,8 @@ then
 fi
 git submodule update
 
+popd
+
 which gnome-autogen.sh || {
     echo "You need to install gnome-common from GNOME Git (or from"
     echo "your OS vendor's package manager)."