RFR: Enable TLHS by default (again)

[Aleksey Shipilev]

On 11/14/2018 05:11 PM, Roman Kennke wrote:
>> Adding the simple regression test
>> with TLHS specifically enabled would be nice, though.
> 
> The problem with that is that TLHS did work for most code from day 1,
> the only program that I remember being problematic is serial benchmark,
> and then only with traversal mode. That hardly qualifies as 'simple
> regression test' that we could include in our jtreg tests. We could,
> however, add something to CI that runs this specific setup nightly? In
> the future, should we have have an actual use-case for TLHS, we could
> look at those CI jobs and have some confidence that it's now safe to
> enable TLHS?

Yeah, we can do that.

-Aleksey