[mutter] build: Require bash for pushd

[Jonas Ã…dahl <jadahl src gnome org>]

commit a4cb1f0f7ab278d8a2effa06bc19cfaf00408921
Author: Philip Chimento <philip endlessm com>
Date:   Wed Apr 12 17:50:47 2017 -0700

    build: Require bash for pushd
    
    If using sh, there's no pushd. Make autogen.sh execute with bash instead.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=781242

 autogen.sh |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/autogen.sh b/autogen.sh
index ab81914..ba92763 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 # Run this to generate all the initial makefiles, etc.
 
 srcdir=`dirname $0`