Trust Token Implementation.

Trust Token implementation based on PrivacyPass using the PMBToken construction.
This implementation currently omits the DLEQ proofs.

https://github.com/alxdavids/privacy-pass-ietf/blob/master/draft-davidson-pp-protocol.md
https://eprint.iacr.org/2020/072.pdf

Change-Id: If236cc8beaf33a80bdad2991c3163f9dd0cb7571
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/39244
Commit-Queue: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
diff --git a/include/openssl/base.h b/include/openssl/base.h
index 8d73f77..7218967 100644
--- a/include/openssl/base.h
+++ b/include/openssl/base.h
@@ -422,6 +422,9 @@
 typedef struct ssl_st SSL;
 typedef struct ssl_ticket_aead_method_st SSL_TICKET_AEAD_METHOD;
 typedef struct st_ERR_FNS ERR_FNS;
+typedef struct trust_token_st TRUST_TOKEN;
+typedef struct trust_token_client_st TRUST_TOKEN_CLIENT;
+typedef struct trust_token_issuer_st TRUST_TOKEN_ISSUER;
 typedef struct v3_ext_ctx X509V3_CTX;
 typedef struct x509_attributes_st X509_ATTRIBUTE;
 typedef struct x509_cert_aux_st X509_CERT_AUX;