http: fix compilation with LibreSSL
LibreSSL defines OPENSSL_VERSION_NUMBER to 0x20000000L, but its API is compatible with OpenSSL 1.0.1. Therefore redefine OPENSSL_VERSION_NUMBER to 0x1000115fL (1.0.1u) if LibreSSL is used.
Fixes: #2327 (closed)
LibreSSL defines OPENSSL_VERSION_NUMBER to 0x20000000L, but its API is compatible with OpenSSL 1.0.1. Therefore redefine OPENSSL_VERSION_NUMBER to 0x1000115fL (1.0.1u) if LibreSSL is used.
Fixes: #2327 (closed)