Fix BIO_* functions method linking when compiled with libressl.

ref:
https://github.com/gentoo/libressl/blob/672ac74ce7b7cb2e4799b2d66bc0b1b1efa3454e/media-video/ffmpeg/files/ffmpeg-3.2-libressl.patch

src/openssl_stream.h

@@ -27,7 +27,7 @@ extern int git_openssl_stream_new(git_stream **out, const char *host, const char
 
 
 
-# if OPENSSL_VERSION_NUMBER < 0x10100000L
+# if OPENSSL_VERSION_NUMBER < 0x10100000L || defined(LIBRESSL_VERSION_NUMBER)
 
 GIT_INLINE(BIO_METHOD*) BIO_meth_new(int type, const char *name)
 {