Secure logs format string

Secure logs format string

This patch makes compilers happy. Some of them complain,
if -werror=format-security flag was enabled about insecure format
string, that is created using stringstream.

This patch defines own format string "%s" if there are no additional
parameters except format string passed to LOGX macros.

The drawback of this solution is that usage of %m is not supported
if there are no additional arguments to LOG (beside format message).

Change-Id: I2d4ab5a07d170c85f162a5f59cb63ecbfb56fec6