Add tests for protected setOption method

Bug: 217902661
Test: atest CtsLibcoreTestCases:org.apache.harmony.tests.java.net.DatagramSocketImplTest
Test: atest CtsLibcoreTestCases:libcore.java.net.SocketTest
Change-Id: I7f1ad3c93e3b98a7d8a5ed62b9dfc650f395b3bd
2 files changed