Unexport ASN1_OBJECT_new.

Outside the library, this function is practically useless. It creates an
empty ASN1_OBJECT, which can never be filled in because the struct is
private and there are no mutating setters.

(See https://boringssl-review.googlesource.com/c/boringssl/+/46164 and
https://boringssl-review.googlesource.com/c/boringssl/+/48326 for a
discussion on why it's important ASN1_OBJECTs are immutable.)

Update-Note: ASN1_OBJECT_new is no longer exported. While this function
does remain in OpenSSL, it is extremely unlikely anyone has found a use
for this function.

Bug: 452
Change-Id: I111a9a1ce3ca4d7aa717a3c3a03d34c05af8fdbd
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/50025
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>

crypto/asn1/internal.h

@@ -106,6 +106,8 @@ struct asn1_object_st {
   int flags;                 /* Should we free this one */
 };
 
+ASN1_OBJECT *ASN1_OBJECT_new(void);
+
 int asn1_utctime_to_tm(struct tm *tm, const ASN1_UTCTIME *d);
 int asn1_generalizedtime_to_tm(struct tm *tm, const ASN1_GENERALIZEDTIME *d);
 

include/openssl/asn1.h

@@ -1618,7 +1618,6 @@ typedef int i2d_of_void(const void *, unsigned char **);
 #define B_ASN1_DISPLAYTEXT \
   B_ASN1_IA5STRING | B_ASN1_VISIBLESTRING | B_ASN1_BMPSTRING | B_ASN1_UTF8STRING
 
-OPENSSL_EXPORT ASN1_OBJECT *ASN1_OBJECT_new(void);
 OPENSSL_EXPORT void ASN1_OBJECT_free(ASN1_OBJECT *a);
 OPENSSL_EXPORT int i2d_ASN1_OBJECT(const ASN1_OBJECT *a, unsigned char **pp);
 OPENSSL_EXPORT ASN1_OBJECT *c2i_ASN1_OBJECT(ASN1_OBJECT **a,