Adding unit tests for exception classes

Adding tests to cover the following APIs:

java.util.concurrent.BrokenBarrierException.BrokenBarrierException(java.lang.String)
java.util.concurrent.CompletionException.CompletionException()
java.util.concurrent.CompletionException.CompletionException(java.lang.String)                                                                                                                                                                                                        [X] java.util.concurrent.CompletionException.CompletionException(java.lang.String, java.lang.Throwable)
java.util.concurrent.CompletionException.CompletionException(java.lang.String, java.lang.Throwable)
java.util.concurrent.ExecutionException.ExecutionException()
java.util.concurrent.ExecutionException.ExecutionException(java.lang.String)
java.util.concurrent.ExecutionException.ExecutionException(java.lang.String, java.lang.Throwable)
java.util.concurrent.RejectedExecutionException.RejectedExecutionException()
java.util.concurrent.RejectedExecutionException.RejectedExecutionException(java.lang.String, java.lang.Throwable)
java.util.concurrent.RejectedExecutionException.RejectedExecutionException(java.lang.Throwable)

Bug: 182165523
Test: atest CtsLibcoreOjTestCases:BrokenBarrierExceptionTest
Test: atest CtsLibcoreOjTestCases:CompletionExceptionTest
Test: atest CtsLibcoreOjTestCases:ExecutionExceptionTest
Test: atest CtsLibcoreOjTestCases:RejectedExecutionExceptionTest
Change-Id: Idc905cc6baf770ff514adcf9ae00547832271e09
5 files changed