log --stat: use the full terminal width

Make log --stat behave like diff --stat and use the full terminal
width.

Signed-off-by: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/log.c

@@ -77,6 +77,7 @@ static void cmd_log_init_defaults(struct rev_info *rev)
 		get_commit_format(fmt_pretty, rev);
 	rev->verbose_header = 1;
 	DIFF_OPT_SET(&rev->diffopt, RECURSIVE);
+	rev->diffopt.stat_width = -1; /* use full terminal width */
 	rev->abbrev_commit = default_abbrev_commit;
 	rev->show_root_diff = default_show_root;
 	rev->subject_prefix = fmt_patch_subject_prefix;