[libwnck] fix builddir != srcdir

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 6e18f10ac742903d925eb6f5ff75bbbe45da6114
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Sun Apr 30 19:32:20 2017 +0300

    fix builddir != srcdir

 autogen.sh |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/autogen.sh b/autogen.sh
index 6f5ad11..6def199 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -27,6 +27,8 @@ gtkdocize --copy || exit 1
 autoreconf --verbose --force --install -Wno-portability || exit 1
 { set +x; } 2>/dev/null
 
+cd "$olddir"
+
 if [ -z "$NOCONFIGURE" ]; then
   set -x
   $srcdir/configure "$@" || exit 1