The dawn.h and dawncpp.h structure definitions references dawnFoo or
dawn::Foo respectively when it should reference dawn_native::FooBase* in
dawn_native. Autogenerate files to declare the dawn_native version of
the structs and change the ProcTable generation to use it instead.
This is important to make libdawn_native a shared library because
currently it was depending on dawncpp's definition of .Get().
Corentin Wallez