sequencer: use memoized sequencer directory path

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/commit.c

@@ -183,7 +183,7 @@ static void determine_whence(struct wt_status *s)
 		whence = FROM_MERGE;
 	else if (file_exists(git_path_cherry_pick_head())) {
 		whence = FROM_CHERRY_PICK;
-		if (file_exists(git_path(SEQ_DIR)))
+		if (file_exists(git_path_seq_dir()))
 			sequencer_in_use = 1;
 	}
 	else

sequencer.c

@@ -21,10 +21,11 @@
 const char sign_off_header[] = "Signed-off-by: ";
 static const char cherry_picked_prefix[] = "(cherry picked from commit ";
 
-static GIT_PATH_FUNC(git_path_todo_file, SEQ_TODO_FILE)
-static GIT_PATH_FUNC(git_path_opts_file, SEQ_OPTS_FILE)
-static GIT_PATH_FUNC(git_path_seq_dir, SEQ_DIR)
-static GIT_PATH_FUNC(git_path_head_file, SEQ_HEAD_FILE)
+GIT_PATH_FUNC(git_path_seq_dir, "sequencer")
+
+static GIT_PATH_FUNC(git_path_todo_file, "sequencer/todo")
+static GIT_PATH_FUNC(git_path_opts_file, "sequencer/opts")
+static GIT_PATH_FUNC(git_path_head_file, "sequencer/head")
 
 static int is_rfc2822_line(const char *buf, int len)
 {
@@ -112,7 +113,7 @@ static void remove_sequencer_state(void)
 {
 	struct strbuf seq_dir = STRBUF_INIT;
 
-	strbuf_addstr(&seq_dir, git_path(SEQ_DIR));
+	strbuf_addstr(&seq_dir, git_path_seq_dir());
 	remove_dir_recursively(&seq_dir, 0);
 	strbuf_release(&seq_dir);
 }

sequencer.h

@@ -1,10 +1,7 @@
 #ifndef SEQUENCER_H
 #define SEQUENCER_H
 
-#define SEQ_DIR		"sequencer"
-#define SEQ_HEAD_FILE	"sequencer/head"
-#define SEQ_TODO_FILE	"sequencer/todo"
-#define SEQ_OPTS_FILE	"sequencer/opts"
+const char *git_path_seq_dir(void);
 
 #define APPEND_SIGNOFF_DEDUP (1u << 0)