Don't use 'tt' uninitialized when reporting an error

(we don't have an ASN1_TEMPLATE to complain about at this stage,
so  errtt == NULL  should be OK)

crypto/asn1/tasn_dec.c

@@ -231,7 +231,6 @@ int ASN1_item_ex_d2i(ASN1_VALUE **pval, unsigned char **in, long len, const ASN1
 		/* Allocate structure */
 		if(!*pval) {
 			if(!ASN1_item_ex_new(pval, it)) {
-				errtt = tt;
 				ASN1err(ASN1_F_ASN1_ITEM_EX_D2I, ERR_R_NESTED_ASN1_ERROR);
 				goto err;
 			}