worktree.c: rewrite mark_current_worktree() to avoid strbuf

strbuf is a bit overkill for this function. What we need is to call
absolute_path() twice and make sure the second call does not destroy the
result of the first. One buffer allocation is enough.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

worktree.c

@@ -153,21 +153,19 @@ done:
 
 static void mark_current_worktree(struct worktree **worktrees)
 {
-	struct strbuf git_dir = STRBUF_INIT;
-	struct strbuf path = STRBUF_INIT;
+	char *git_dir = xstrdup(absolute_path(get_git_dir()));
 	int i;
 
-	strbuf_addstr(&git_dir, absolute_path(get_git_dir()));
 	for (i = 0; worktrees[i]; i++) {
 		struct worktree *wt = worktrees[i];
-		strbuf_addstr(&path, absolute_path(get_worktree_git_dir(wt)));
-		wt->is_current = !fspathcmp(git_dir.buf, path.buf);
-		strbuf_reset(&path);
-		if (wt->is_current)
+		const char *wt_git_dir = get_worktree_git_dir(wt);
+
+		if (!fspathcmp(git_dir, absolute_path(wt_git_dir))) {
+			wt->is_current = 1;
 			break;
+		}
 	}
-	strbuf_release(&git_dir);
-	strbuf_release(&path);
+	free(git_dir);
 }
 
 struct worktree **get_worktrees(void)