ALL: Investigate improving unit testing around low level native calls

[jpaskhay]

There are a few empty unit test cases that have yet to be implemented in Java and C# (LibcProtectedMemoryAllocatorTest in particular). The affected library source code is covered via other unit tests that are in place, but some of the low level native calls are difficult to unit test in the traditional sense. We could theoretically setup functional/integration tests to cover them.