Add option to do strict unwind checks in gcstress

Check that the obtained backtraces are complete.

This ensures that the gcstress test works as expected.

It is also stress test of the unwinder (especially for JIT).

This CL leaves the option off, to make reverts trivial.

Test: art/test.py -b -r --jit --host --gcstress
Change-Id: I64a4abc85a0cb35bda68a0e84e5848d48ea156a9
2 files changed