TSan: Move suppressions to source file.

Chromium has deprecated text-file based suppressions for
TSan (v2) and is about to remove the support for it in the
test toolchain in https://codereview.chromium.org/357673002/

This CL moves our suppressions to a source file (based on the
Chromium copy).
It also moves the sanitizer_options.gyp into webrtc/build.

BUG=chromium:302040
TEST=Locally executing all the standalone tests under TSan v2.
R=niklas.enbom@webrtc.org, pbos@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/14759004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6552 4adac7df-926f-26a2-2b94-8c16560cd09d