Enable HKDF support for LibreSSL 3.6 and later

LibreSSL 3.6 added support for HKDF in EVP. Enable this in ossl_kdf.c.

Author: botovq

ext/openssl/ossl_kdf.c

@@ -3,7 +3,7 @@
  * Copyright (C) 2007, 2017 Ruby/OpenSSL Project Authors
  */
 #include "ossl.h"
-#if OPENSSL_VERSION_NUMBER >= 0x10100000 && !defined(LIBRESSL_VERSION_NUMBER)
+#if OSSL_OPENSSL_PREREQ(1, 1, 0) || OSSL_LIBRESSL_PREREQ(3, 6, 0)
 # include <openssl/kdf.h>
 #endif
 
@@ -141,7 +141,7 @@ kdf_scrypt(int argc, VALUE *argv, VALUE self)
 }
 #endif
 
-#if OPENSSL_VERSION_NUMBER >= 0x10100000 && !defined(LIBRESSL_VERSION_NUMBER)
+#if OSSL_OPENSSL_PREREQ(1, 1, 0) || OSSL_LIBRESSL_PREREQ(3, 6, 0)
 /*
  * call-seq:
  *    KDF.hkdf(ikm, salt:, info:, length:, hash:) -> String
@@ -305,7 +305,7 @@ Init_ossl_kdf(void)
 #if defined(HAVE_EVP_PBE_SCRYPT)
     rb_define_module_function(mKDF, "scrypt", kdf_scrypt, -1);
 #endif
-#if OPENSSL_VERSION_NUMBER >= 0x10100000 && !defined(LIBRESSL_VERSION_NUMBER)
+#if OSSL_OPENSSL_PREREQ(1, 1, 0) || OSSL_LIBRESSL_PREREQ(3, 6, 0)
     rb_define_module_function(mKDF, "hkdf", kdf_hkdf, -1);
 #endif
 }