Add -Xjniopts:forcecopy-unmap to catch more errors than forcecopy.

In particular, this spots the BreakIterator bug that forcecopy didn't.
It's about 2x slower than regular forcecopy mode, so I've added a new
option rather than just replace the fast-but-less-effective forcecopy.

Bug: 3412449
Change-Id: I1f226ceeab2508dff607ba25b0afee51cf9c3f83
6 files changed