Make localedir work in build with autoconf 2.5x

autoconf 2.5x does not define localedir, so we have to detect that and
do it ourselves.

https://github.com/krb5/krb5/commit/6abd6ef1d125af12dcf061d677e4315195be4e27
Commit By: ghudson
Revision: 25777
Changed Files:
U   trunk/src/configure.in