package/autoconf: bump to version 2.71

- Update hash of license files due to links being updated:
  http://git.savannah.gnu.org/gitweb/?p=autoconf.git;a=commit;h=61024bf52ba8a58f8992490134280eb9575e2525
- Update indentation in hash file (two spaces)

https://git.savannah.gnu.org/cgit/autoconf.git/tree/NEWS?h=v2.71



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>