Fix warning and back out bad modification.

engines/ccgost/gost_crypt.c

@@ -565,7 +565,7 @@ int gost_imit_init_cpa(EVP_MD_CTX *ctx)
 
 static void mac_block_mesh(struct ossl_gost_imit_ctx *c,const unsigned char *data)
 	{
-	char buffer[8];
+	unsigned char buffer[8];
 	/* We are using local buffer for iv because CryptoPro doesn't 
 	 * interpret internal state of MAC algorithm as iv during keymeshing
 	 * (but does initialize internal state from iv in key transport

engines/ccgost/gost_pmeth.c

@@ -591,7 +591,7 @@ static int pkey_gost_mac_ctrl (EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
 				} else {
 				key = &(data->key);
 				}
-			return imit_gost_vizir.md_ctrl(mctx,EVP_MD_CTRL_SET_KEY,32,key);
+			return mctx->digest->md_ctrl(mctx,EVP_MD_CTRL_SET_KEY,32,key);
 			}  
 		}	
 	return -2;