patchgit-svn fix to avoid using strftime %z

> %z isn't available on all platforms in the date formatting
> routines.  Provide a workalike capability that should be
> more portable.
> 
> Signed-off-by: Ben Walton <bwalton@artsci.utoronto.ca>

> ---
> This is the reworked version that was requested.  It drops %z completely
> from the strftime call in favour of the hand rolled version.  All tests
> still pass on Linux and Solaris.
> 
>  git-svn.perl |    8 +++++++-
>  1 files changed, 7 insertions(+), 1 deletions(-)
> 
> diff --git a/git-svn.perl b/git-svn.perl
> index cbc5211..24180eb 100755
> --- a/git-svn.perl
> +++ b/git-svn.perl
> @@ -4615,6 +4615,7 @@ package Git::SVN::Log;
>  use strict;
>  use warnings;
>  use POSIX qw/strftime/;
> +use Time::Local;
>  use constant commit_log_separator => ('-' x 72) . "\n";
>  use vars qw/$TZ $limit $color $pager $non_recursive $verbose $oneline
>              %rusers $show_commit $incremental/;
> @@ -4721,7 +4722,12 @@ sub run_pager {
>  }
>  
>  sub format_svn_date {
> -	return strftime("%Y-%m-%d %H:%M:%S %z (%a, %d %b %Y)", localtime(shift));
> +	# some systmes don't handle or mishandle %z, so be creative.
> +	my $t = shift;
> +	my $gm = timelocal(gmtime($t));
> +	my $sign = qw( + + - )[ $t <=> $gm ];
> +	my $gmoff = sprintf("%s%02d%02d", $sign, (gmtime(abs($t - $gm)))[2,1]);
> +	return strftime("%Y-%m-%d %H:%M:%S $gmoff (%a, %d %b %Y)", localtime($t));
>  }
>  
>  sub parse_git_date {