sequencer: rename amend_author to author_to_rename

The purpose of amend_author was to free() the malloc()'d string
obtained from get_author() while amending a commit. But we can
also use the variable to free() the author at our convenience.
Rename it to convey this meaning.

Signed-off-by: Rohit Ashiwal <rohit.ashiwal265@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sequencer.c

@@ -1354,7 +1354,7 @@ static int try_to_commit(struct repository *r,
 	struct commit_extra_header *extra = NULL;
 	struct strbuf err = STRBUF_INIT;
 	struct strbuf commit_msg = STRBUF_INIT;
-	char *amend_author = NULL;
+	char *author_to_free = NULL;
 	const char *hook_commit = NULL;
 	enum commit_msg_cleanup_mode cleanup;
 	int res = 0;
@@ -1375,7 +1375,7 @@ static int try_to_commit(struct repository *r,
 			strbuf_addstr(msg, orig_message);
 			hook_commit = "HEAD";
 		}
-		author = amend_author = get_author(message);
+		author = author_to_free = get_author(message);
 		unuse_commit_buffer(current_head, message);
 		if (!author) {
 			res = error(_("unable to parse commit author"));
@@ -1474,7 +1474,7 @@ out:
 	free_commit_extra_headers(extra);
 	strbuf_release(&err);
 	strbuf_release(&commit_msg);
-	free(amend_author);
+	free(author_to_free);
 
 	return res;
 }