decode_85(): fix missing return.

When the function detected an invalid base85 sequence, it issued
an error message but forgot to return error status at that point
and kept going.

Signed-off-by: Jerald Fitzjerald <jfj@freemail.gr>
Signed-off-by: Junio C Hamano <junkio@cox.net>

base85.c

@@ -66,7 +66,7 @@ int decode_85(char *dst, const char *buffer, int len)
 		 */
 		if (0x03030303 < acc ||
 		    0xffffffff - de < (acc *= 85))
-			error("invalid base85 sequence %.5s", buffer-5);
+			return error("invalid base85 sequence %.5s", buffer-5);
 		acc += de;
 		say1(" %08x", acc);