[rwlock] Added test "Read-Die-Write".

This test checks that exceptions in RWLock::Read are handled properly. Problem occurs when implementor forgets to add try-catch statement around func() with a cleanup in catch block. I have passed all tests without try-catch.

Also currently there are no tests for the same issue in Write. I tried to write some test, but it is not so easy. It is much more easier to use Twist for such testing.