mktag: use puts(str) instead of printf("%s\n", str)

This introduces no functional change, but refactors the print-out of
the hash at the end to do the same thing with less code.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/mktag.c

@@ -173,6 +173,6 @@ int cmd_mktag(int argc, const char **argv, const char *prefix)
 		die("unable to write tag file");
 
 	strbuf_release(&buf);
-	printf("%s\n", oid_to_hex(&result));
+	puts(oid_to_hex(&result));
 	return 0;
 }