Free compressed buffer after write_sha1_file() is done.

This does not matter for commands that write just a handful SHA1 files,
but is noticeable in git-convert-cache which essentially traverses the
entire object database.

Signed-off-by: Junio C Hamano <junkio@cox.net>

sha1_file.c

@@ -425,6 +425,7 @@ int write_sha1_file(char *buf, unsigned long len, const char *type, unsigned cha
 		die("unable to write file");
 	fchmod(fd, 0444);
 	close(fd);
+	free(compressed);
 
 	ret = link(tmpfile, filename);
 	if (ret < 0) {