options: Introduce ssh_bind_options_parse_config()

The added API allows setting the options of a given bind context through
a configuration file.  The default global configuration file
"/etc/ssh/libssh_server_config" is parsed before the provided
configuration file, if it hasn't been parsed yet.

Signed-off-by: Anderson Toshiyuki Sasaki <ansasaki@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

include/libssh/server.h

@@ -90,6 +90,9 @@ LIBSSH_API ssh_bind ssh_bind_new(void);
 LIBSSH_API int ssh_bind_options_set(ssh_bind sshbind,
     enum ssh_bind_options_e type, const void *value);
 
+LIBSSH_API int ssh_bind_options_parse_config(ssh_bind sshbind,
+    const char *filename);
+
 /**
  * @brief Start listening to the socket.
  *