polarssl: add easy logging for PolarSSL errors

polarssl: add easy logging for PolarSSL errors

Add the functions polar_log_err(), polar_log_func_line() and a macro
polar_ok(), to easily log human-readable PolarSSL errors from
polarssl-specific code.

This does not provide the full logging interface as msg(), because I
would have to add a lot more of macro-magic to achieve that on the
various supported compilers and platforms, and this suffices too (for
now at least).

Signed-off-by: Steffan Karger <steffan@karger.me>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1425810005-11893-1-git-send-email-steffan@karger.me>
URL: http://article.gmane.org/gmane.network.openvpn.devel/9528
Signed-off-by: Gert Doering <gert@greenie.muc.de>