This cleans up any potential problems with allocating and freeing
resources in different shared objects or DLLs. Previously we were
using a dynamically linked allocation function and then calling
the standard delete function.

Also adds a base class helper for EGLWindow. Will base the WGL
Window class on this.

Needed for running ANGLE tests against native drivers.

Bug: angleproject:2995
Change-Id: Ic92b447649ebb32c547605c20086c07a601842f0
Reviewed-on: https://chromium-review.googlesource.com/c/1393443
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>