[PATCH] builtin/gc.c: fix -Wdeclaration-after-statement

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

In 1f80129d61b (maintenance: add option to register in a specific
config, 2022-11-09) code was added which triggers a
"-Wdeclaration-after-statement" warning, which is on by default with
DEVELOPER=1.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---

This landed in the latest "next" push-out, causing e.g this CI
failure:
https://github.com/git/git/actions/runs/3467538041/jobs/5792504315

 builtin/gc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/builtin/gc.c b/builtin/gc.c
index 56b107e7f0b..22a990db0be 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -1543,6 +1543,7 @@ static int maintenance_unregister(int argc, const char **argv, const char *prefi
 	int found = 0;
 	struct string_list_item *item;
 	const struct string_list *list;
+	struct config_set cs;
 
 	argc = parse_options(argc, argv, prefix, options,
 			     builtin_maintenance_unregister_usage, 0);
@@ -1550,7 +1551,6 @@ static int maintenance_unregister(int argc, const char **argv, const char *prefi
 		usage_with_options(builtin_maintenance_unregister_usage,
 				   options);
 
-	struct config_set cs;
 	if (config_file) {
 		git_configset_init(&cs);
 		git_configset_add_file(&cs, config_file);
-- 
2.38.0.1473.g172bcc0511c