Fix ASN1_INTEGER handling.

Only treat an ASN1_ANY type as an integer if it has the V_ASN1_INTEGER
tag: V_ASN1_NEG_INTEGER is an internal only value which is never used
for on the wire encoding.

Thanks to David Benjamin <davidben@google.com> for reporting this bug.

This was found using libFuzzer.

RT#4364 (part)CVE-2016-2108.

Reviewed-by: Emilia Käsper <emilia@openssl.org>

crypto/asn1/a_type.c

@@ -122,9 +122,7 @@ int ASN1_TYPE_cmp(const ASN1_TYPE *a, const ASN1_TYPE *b)
         result = 0;             /* They do not have content. */
         break;
     case V_ASN1_INTEGER:
-    case V_ASN1_NEG_INTEGER:
     case V_ASN1_ENUMERATED:
-    case V_ASN1_NEG_ENUMERATED:
     case V_ASN1_BIT_STRING:
     case V_ASN1_OCTET_STRING:
     case V_ASN1_SEQUENCE:

crypto/asn1/tasn_dec.c

@@ -858,9 +858,7 @@ static int asn1_ex_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
         break;
 
     case V_ASN1_INTEGER:
-    case V_ASN1_NEG_INTEGER:
     case V_ASN1_ENUMERATED:
-    case V_ASN1_NEG_ENUMERATED:
         tint = (ASN1_INTEGER **)pval;
         if (!c2i_ASN1_INTEGER(tint, &cont, len))
             goto err;

crypto/asn1/tasn_enc.c

@@ -600,9 +600,7 @@ static int asn1_ex_i2c(ASN1_VALUE **pval, unsigned char *cout, int *putype,
                                    cout ? &cout : NULL);
 
     case V_ASN1_INTEGER:
-    case V_ASN1_NEG_INTEGER:
     case V_ASN1_ENUMERATED:
-    case V_ASN1_NEG_ENUMERATED:
         /*
          * These are all have the same content format as ASN1_INTEGER
          */