Declare EVP_AEAD_CTX in base.h, like other typedefs.

Change-Id: Ib0dd73fc4b5b50d542a9b937065048ed9b0a85fd
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/52566
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: Adam Langley <agl@google.com>
diff --git a/include/openssl/base.h b/include/openssl/base.h
index b630236..2f03bca 100644
--- a/include/openssl/base.h
+++ b/include/openssl/base.h
@@ -402,6 +402,7 @@
 typedef struct env_md_ctx_st EVP_MD_CTX;
 typedef struct env_md_st EVP_MD;
 typedef struct evp_aead_st EVP_AEAD;
+typedef struct evp_aead_ctx_st EVP_AEAD_CTX;
 typedef struct evp_cipher_ctx_st EVP_CIPHER_CTX;
 typedef struct evp_cipher_st EVP_CIPHER;
 typedef struct evp_encode_ctx_st EVP_ENCODE_CTX;