git-commit: replace use of home_config_paths()

Since home_config_paths() combines two distinct functionality already
implemented by expand_user_path() and xdg_config_home(), and hides the
home config file path ~/.gitconfig. Make the code more explicit by
replacing the use of home_config_paths() with expand_user_path() and
xdg_config_home().

Signed-off-by: Paul Tan <pyokagan@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/commit.c b/builtin/commit.c
index 7d90c35..b4aaaab 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1402,12 +1402,10 @@
 
 static const char *implicit_ident_advice(void)
 {
-	char *user_config = NULL;
-	char *xdg_config = NULL;
-	int config_exists;
+	char *user_config = expand_user_path("~/.gitconfig");
+	char *xdg_config = xdg_config_home("config");
+	int config_exists = file_exists(user_config) || file_exists(xdg_config);
 
-	home_config_paths(&user_config, &xdg_config, "config");
-	config_exists = file_exists(user_config) || file_exists(xdg_config);
 	free(user_config);
 	free(xdg_config);