SSL: reasonable version for LibreSSL. LibreSSL defines OPENSSL_VERSION_NUMBER to 0x20000000L, but uses an old API derived from OpenSSL at the time LibreSSL forked. As a result, every version check we use to test for new API elements in newer OpenSSL versions requires an explicit check for LibreSSL. To reduce clutter, redefine OPENSSL_VERSION_NUMBER to 0x1000107fL if LibreSSL is used. The same is done by FreeBSD port of LibreSSL.

--- a/src/event/ngx_event_openssl.h
+++ b/src/event/ngx_event_openssl.h
@@ -33,6 +33,12 @@
 #define NGX_SSL_NAME     "OpenSSL"
 
 
+#if (defined LIBRESSL_VERSION_NUMBER && OPENSSL_VERSION_NUMBER == 0x20000000L)
+#undef OPENSSL_VERSION_NUMBER
+#define OPENSSL_VERSION_NUMBER  0x1000107fL
+#endif
+
+
 #define ngx_ssl_session_t       SSL_SESSION
 #define ngx_ssl_conn_t          SSL