[tsan] ThreadSanitizer instrumentation part

[Jakub Jelinek]

On Fri, Nov 02, 2012 at 08:54:42AM -0700, Xinliang David Li wrote:
> Thanks, good to know that.

But note that such vars, even when accessed only partially, don't
need to be tracked by tsan just because of that.
TREE_ADDRESSABLE (decl) || is_global_var (decl) is really a conservative
check for what needs to be tracked, and perhaps less conservative one using
points-to.

	Jakub