CDRIVER-1941 Fix libressl build

Author: bjori

src/mongoc/mongoc-init.c

@@ -28,6 +28,8 @@
 # include "mongoc-ssl.h"
 # ifdef MONGOC_ENABLE_SSL_OPENSSL
 #  include "mongoc-openssl-private.h"
+#elif defined(MONGOC_ENABLE_SSL_LIBRESSL)
+#  include "tls.h"
 # endif
 #endif
 #include "mongoc-thread-private.h"

src/mongoc/mongoc-libressl.c

@@ -45,7 +45,7 @@ mongoc_libressl_setup_certificate (mongoc_stream_tls_libressl_t *libressl,
       return false;
    }
 
-   file = tls_load_file (opt->pem_file, &file_len, opt->pem_pwd);
+   file = tls_load_file (opt->pem_file, &file_len, (char *)opt->pem_pwd);
    if (!file) {
       return false;
    }

src/mongoc/mongoc-ssl.c

@@ -80,6 +80,7 @@ mongoc_ssl_extract_subject (const char *filename, const char *passphrase)
 #elif defined(MONGOC_ENABLE_SSL_LIBRESSL)
     MONGOC_WARNING ("libtls doesn't support automatically extracting subject from "
                     "certificate to use with authentication");
+    retval = NULL;
 #elif defined(MONGOC_ENABLE_SSL_SECURE_TRANSPORT)
 	retval = _mongoc_secure_transport_extract_subject (filename, passphrase);
 #elif defined(MONGOC_ENABLE_SSL_SECURE_CHANNEL)

src/mongoc/mongoc-stream-tls-libressl.c

@@ -501,7 +501,6 @@ mongoc_stream_tls_libressl_new (mongoc_stream_t  *base_stream,
 
    }
 
-   libressl->n = streams++;
    mongoc_counter_streams_active_inc();
    RETURN((mongoc_stream_t *)tls);
 }