Add cts test for detect/permit unbuffered IO.

Bug: 208243190
Bug: 207016502
Test: atest StrictModeTest#testThreadBuilder_detectUnbufferedIo
Test: atest StrictModeTest#testThreadBuilder_permitUnbufferedIo
Change-Id: I6f8d1e86e4ac88ce34639f98f6348b97eedbe0f6
Merged-In: I6f8d1e86e4ac88ce34639f98f6348b97eedbe0f6
(cherry picked from commit 6710208b00c3c398d7ee81251800b8e34318504a)
1 file changed