Rename env_md{,_ctx}_st to evp_md{,_ctx}_st

As everyone knows (and who doesn't know will immediately guess), EVP is
short for envelope. Most structs backing the public EVP_* types are called
evp_*. For the EVP_MD and EVP_MD_CTX types, someone used env_md_st and
env_md_ctx_st, which, as jsing pointed out, may or may not be related to
a much less obvious abbreviation of envelope. It could also simply have
been for reasons of inconsistency.

Be all that as it may: rename these structs to use the evp_* namespace
to match all the other EVP types, as well as upstream.

ok jsing

lib/libcrypto/evp/evp_local.h

@@ -1,4 +1,4 @@
-/* $OpenBSD: evp_local.h,v 1.3 2023/03/01 11:16:06 tb Exp $ */
+/* $OpenBSD: evp_local.h,v 1.4 2023/08/11 05:10:35 tb Exp $ */
 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
  * project 2000.
  */
@@ -115,7 +115,7 @@ struct evp_pkey_st {
 	STACK_OF(X509_ATTRIBUTE) *attributes; /* [ 0 ] */
 } /* EVP_PKEY */;
 
-struct env_md_st {
+struct evp_md_st {
 	int type;
 	int pkey_type;
 	int md_size;
@@ -132,7 +132,7 @@ struct env_md_st {
 	int (*md_ctrl)(EVP_MD_CTX *ctx, int cmd, int p1, void *p2);
 } /* EVP_MD */;
 
-struct env_md_ctx_st {
+struct evp_md_ctx_st {
 	const EVP_MD *digest;
 	ENGINE *engine; /* functional reference if 'digest' is ENGINE-provided */
 	unsigned long flags;

lib/libcrypto/ossl_typ.h

@@ -1,4 +1,4 @@
-/* $OpenBSD: ossl_typ.h,v 1.29 2023/08/11 04:45:26 tb Exp $ */
+/* $OpenBSD: ossl_typ.h,v 1.30 2023/08/11 05:10:35 tb Exp $ */
 /* ====================================================================
  * Copyright (c) 1998-2001 The OpenSSL Project.  All rights reserved.
  *
@@ -99,8 +99,8 @@ typedef struct comp_method_st COMP_METHOD;
 
 typedef struct evp_cipher_st EVP_CIPHER;
 typedef struct evp_cipher_ctx_st EVP_CIPHER_CTX;
-typedef struct env_md_st EVP_MD;
-typedef struct env_md_ctx_st EVP_MD_CTX;
+typedef struct evp_md_st EVP_MD;
+typedef struct evp_md_ctx_st EVP_MD_CTX;
 typedef struct evp_pkey_st EVP_PKEY;
 
 typedef struct evp_pkey_asn1_method_st EVP_PKEY_ASN1_METHOD;