MINOR: htx: Add proto_htx.c file

This file is empty for now. But it will be used to add new versions of the HTTP
analyzers based on the internal representation of HTTP messages (not implemented
yet but called HTX).
diff --git a/src/proto_htx.c b/src/proto_htx.c
new file mode 100644
index 0000000..ec29cbc
--- /dev/null
+++ b/src/proto_htx.c
@@ -0,0 +1,24 @@
+/*
+ * HTTP protocol analyzer
+ *
+ * Copyright (C) 2018 HAProxy Technologies, Christopher Faulet <cfaulet@haproxy.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ */
+
+__attribute__((constructor))
+static void __htx_protocol_init(void)
+{
+}
+
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ */