Guillaume Roguez authored Aug 29, 2017 and Andreas Traczyk committed Aug 31, 2017

This refactoring of logger brings a definitive C++ orientation
of the code.

A Logger class is added with the support of two logging fashions:
* legacy printf style (format string + optional arguments)
* the iostream C++ style using << operator

This patch doesn't break retro-compatility, but change a bit the
logging output of filename/line context.
This change is needed to not increase the overhead
compared to situation before the patch and let us open to chose how
to display this information without the need to re-build the code.

Also change some macros where RING_xxx are used conjointly with
__VA_ARGS__ to make them work on VisualStudio (UWP) with this new API.

Change-Id: Iaea118460cbb31d0eeada9476d4576f675a9b056
Reviewed-by: Andreas Traczyk <andreas.traczyk@savoirfairelinux.com>