pretty: --format output should honor logOutputEncoding

One can set an alias
	$ git config [--global] alias.lg "log --graph --pretty=format:'%Cred%h%Creset
	-%C(yellow)%d%Creset %s %Cgreen(%cd) %C(bold blue)<%an>%Creset'
	--abbrev-commit --date=local"

to see the log as a pretty tree (like *gitk* but in a terminal).

However, log messages written in an encoding i18n.commitEncoding which differs
from terminal encoding are shown corrupted even when i18n.logOutputEncoding
and terminal encoding are the same (e.g. log messages committed on a Cygwin box
with Windows-1251 encoding seen on a Linux box with a UTF-8 encoding and vice versa).

To simplify an example we can say the following two commands are expected
to give the same output to a terminal:

	$ git log --oneline --no-color
	$ git log --pretty=format:'%h %s'

However, the former pays attention to i18n.logOutputEncoding
configuration, while the latter does not when it formats "%s".

The same corruption is true for
	$ git diff --submodule=log
and
	$ git rev-list --pretty=format:%s HEAD
and
	$ git reset --hard

This patch makes pretty --format honor logOutputEncoding when it formats
log message.

Signed-off-by: Alexey Shumkin <Alex.Crezoff@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

log-tree.c

@@ -616,6 +616,7 @@ void show_log(struct rev_info *opt)
 	ctx.fmt = opt->commit_format;
 	ctx.mailmap = opt->mailmap;
 	ctx.color = opt->diffopt.use_color;
+	ctx.output_encoding = get_log_output_encoding();
 	pretty_print_commit(&ctx, commit, &msgbuf);
 
 	if (opt->add_signoff)