Copy harmony's jdk6 Math and StrictMath.

There's some ugliness here I want to remove, but it'll be less confusing if
I commit the upstream code first without my changes...

...that said, I've reverted the upstream Math.pow change because it it's just
cruft; we already pass their tests and jtreg's more thorough pow tests (see
http://blogs.sun.com/darcy/entry/finding_a_bug_in_fdlibm). My guess is that
their real problem was that they were using the buggy fdlibm 5.2 until after
they made the Math.pow change. We've always used 5.3, so we were fine.

Change-Id: I5a6c080d9fd6b60dc7bf77ac10096a913766f512
4 files changed