[Sanitizer] Get rid of Symbolizer::Get() and Symbolizer::GetOrNull().

We may as well just use Symbolizer::GetOrInit() in all the cases.
Don't call Symbolizer::Get() early in tools initialization: these days
it doesn't do any important setup work, and we may as well create the
symbolizer the first time it's actually needed.

llvm-svn: 217558
GitOrigin-RevId: 611c906cb3475d82e70ad3564678a9544e79e29c
12 files changed