Hiding the snprintf definition when building with VS2015. https://code.google.com/p/webrtc/issues/d…

Hiding the snprintf definition when building with VS2015. https://code.google.com/p/webrtc/issues/detail?id=5183&thanks=5183&ts=1446960551 Added test for VisualStudio to hide snprintf definition, This is required to build WebRtc on Windows with Visual Studio 2015.

BUG=127

[conceptgenesis, 2015-11-08 05:52:16]

This is my first contribution to Google (or anything OpenSource frankly). So
please educate me if I've done this badly.

This change is part of the fix that I'll be submitting for WebRtc issue 5183.
https://code.google.com/p/webrtc/issues/detail?id=5183&thanks=5183&ts=1446960551

I needed to get WebRtc to build on VS 2015 to take advantage of several new
features in my project. This change is necessary to do that.

[kjellander1, 2015-11-09 05:41:25]

Thanks for offering your help here! Unfortunately the gflags we have in WebRTC
is quite old, and the code location you're trying to update is a read-only
mirror of what gflags code used to live at Google Code.

The gflags project has moved to Github and the change you're trying to make is
already present upstream:
https://github.com/gflags/gflags/blob/master/src/windows_port.cc

I've created https://code.google.com/p/webrtc/issues/detail?id=5185 for bringing
the latest gflags into WebRTC.