grep API: plug memory leaks by freeing "header_list"

When the "header_list" struct member was added in [1], freeing this
field was neglected. Fix that now, so that commands like

	./git -P log -1 --color=always --author=A origin/master

will run leak-free.

1. 80235ba79ef ("log --author=me --grep=it" should find intersection,
   not union, 2010-01-17)

Helped-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/grep.c b/grep.c
index f8708e1fd2..92ece4b7fa 100644
--- a/grep.c
+++ b/grep.c
@@ -795,6 +795,7 @@ static void free_grep_pat(struct grep_pat *pattern)
 void free_grep_patterns(struct grep_opt *opt)
 {
 	free_grep_pat(opt->pattern_list);
+	free_grep_pat(opt->header_list);
 
 	if (opt->pattern_expression)
 		free_pattern_expr(opt->pattern_expression);