Merge branch 'ab/require-perl-5.8' into maint

* ab/require-perl-5.8:
  perl: use "use warnings" instead of -w
  perl: bump the required Perl version to 5.8 from 5.6.[21]

contrib/examples/git-svnimport.perl

@@ -1,4 +1,4 @@
-#!/usr/bin/perl -w
+#!/usr/bin/perl
 
 # This tool is copyright (c) 2005, Matthias Urlichs.
 # It is released under the Gnu Public License, version 2.

contrib/fast-import/import-directories.perl

@@ -1,4 +1,4 @@
-#!/usr/bin/perl -w
+#!/usr/bin/perl
 #
 # Copyright 2008-2009 Peter Krefting <peter@softwolves.pp.se>
 #
@@ -140,6 +140,7 @@ by whitespace or other characters.
 
 # Globals
 use strict;
+use warnings;
 use integer;
 my $crlfmode = 0;
 my @revs;