Could the thread.throwNewException() method use thread.getLoader() instead of thread.getBsCl()

[hrj]

The thread.throwNewException() method is very convenient when throwing exceptions from native code. However, it uses the bootstrap class loader for loading the exception class, making it difficult to throw custom exceptions.

If it uses the loader from getLoader(), user defined exceptions can be easily thrown.

[John Vilk]

Sounds good to me. Feel free to open a PR!