MDEV-10332 support for OpenSSL 1.1 and LibreSSL

post-review fixes:
* move all ssl implementation related ifdefs/defines to one file
  (ssl_compat.h)
* work around OpenSSL-1.1 desire to malloc every EVP context by
  run-time checking that context allocated on the stack is big enough
  (openssl.c)
* use newer version of the AWS SDK for OpenSSL 1.1
* use get_dh2048() function as generated by openssl 1.1
  (viosslfactories.c)

include/ssl_compat.h

@@ -0,0 +1,75 @@
+/*
+ Copyright (c) 2016, 2017 MariaDB Corporation
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; version 2 of the License.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
+
+#include <openssl/opensslv.h>
+
+/* OpenSSL version specific definitions */
+#if !defined(HAVE_YASSL) && defined(OPENSSL_VERSION_NUMBER)
+
+#if OPENSSL_VERSION_NUMBER >= 0x10002000L && !defined(LIBRESSL_VERSION_NUMBER)
+#define HAVE_X509_check_host 1
+#endif
+
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L && !defined(LIBRESSL_VERSION_NUMBER)
+#define HAVE_OPENSSL11 1
+#define ERR_remove_state(X) ERR_clear_error()
+#define EVP_MD_CTX_cleanup(X) EVP_MD_CTX_reset(X)
+#define EVP_CIPHER_CTX_SIZE 168
+#define EVP_MD_CTX_SIZE 48
+#undef EVP_MD_CTX_init
+#define EVP_MD_CTX_init(X) do { bzero((X), EVP_MD_CTX_SIZE); EVP_MD_CTX_reset(X); } while(0)
+#undef EVP_CIPHER_CTX_init
+#define EVP_CIPHER_CTX_init(X) do { bzero((X), EVP_CIPHER_CTX_SIZE); EVP_CIPHER_CTX_reset(X); } while(0)
+
+#else
+#define HAVE_OPENSSL10 1
+/*
+  Unfortunately RAND_bytes manual page does not provide any guarantees
+  in relation to blocking behavior. Here we explicitly use SSLeay random
+  instead of whatever random engine is currently set in OpenSSL. That way
+  we are guaranteed to have a non-blocking random.
+*/
+#define RAND_OpenSSL() RAND_SSLeay()
+
+#ifdef HAVE_ERR_remove_thread_state
+#define ERR_remove_state(X) ERR_remove_thread_state(NULL)
+#endif /* HAVE_ERR_remove_thread_state */
+
+#endif /* HAVE_OPENSSL11 */
+
+#elif defined(HAVE_YASSL)
+#define BN_free(X) do { } while(0)
+#endif /* !defined(HAVE_YASSL) */
+
+#ifndef HAVE_OPENSSL11
+#define ASN1_STRING_get0_data(X)        ASN1_STRING_data(X)
+#define OPENSSL_init_ssl(X,Y)           SSL_library_init()
+#define DH_set0_pqg(D,P,Q,G)            ((D)->p= (P), (D)->g= (G))
+#define EVP_CIPHER_CTX_buf_noconst(ctx) ((ctx)->buf)
+#define EVP_CIPHER_CTX_encrypting(ctx)  ((ctx)->encrypt)
+#define EVP_CIPHER_CTX_SIZE             sizeof(EVP_CIPHER_CTX)
+#define EVP_MD_CTX_SIZE                 sizeof(EVP_MD_CTX)
+#endif
+
+#ifdef	__cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+int check_openssl_compatibility();
+
+#ifdef	__cplusplus
+}
+#endif