Do load libgdx and lwjgl openal natives for the jogl 2 backend.

libgdx implements many low level functions natively thus calling
GdxNativesLoader.load() is mandatory.

libgdx uses lwjgl openal as its only primary audio backend, keep using it.

This change will enable startup of libgdx tests using the jogl 2 backend.

Signed-off-by: Xerxes Rånby <xerxes@zafena.se>