RFR: jsr166 jdk9 integration wave 2

[Martin Buchholz]

We're stuck.  Peter wants to make Throwables cloneable, I want to
reverse the order of throwables and add the past Throwable as a
suppressed exception to the exception of a dependent action, and Doug
wants the current webrev behavior of adding the dependent action as a
suppressed exception of the source.

I'm willing to accept the small incompatibility of throwing a
different exception when everything fails; the existing spec doesn't
promise what happens in this case.