Fix ASN1_STRING_to_UTF8 could not convert NumericString

tag2nbyte had -1 at 18th position, but underlying ASN1_mbstring_copy
supports NumericString. tag2nbyte is also used in do_print_ex which will
not be broken by setting 1 at 18th position of tag2nbyte
Reviewed-by: NStephen Henson <steve@openssl.org>

crypto/asn1/a_strex.c

@@ -282,7 +282,7 @@ static const signed char tag2nbyte[] = {
     -1, -1, -1, -1, -1,         /* 5-9 */
     -1, -1, 0, -1,              /* 10-13 */
     -1, -1, -1, -1,             /* 15-17 */
-    -1, 1, 1,                   /* 18-20 */
+    1, 1, 1,                    /* 18-20 */
     -1, 1, 1, 1,                /* 21-24 */
     -1, 1, -1,                  /* 25-27 */
     4, -1, 2                    /* 28-30 */