Fix 674-hiddenapi run-test on AOSP host

The test would call VMRuntime.setHiddenApiExemptions() to test
whitelisting, but this API is now blacklisted. Add a small native helper
which achieves the same goal to fix the test.

Bug: 123150330
Test: art/test.py -b --host -r -t 674-hiddenapi
Change-Id: I03d6941507c273b53a25d70630807490a608fb59
2 files changed