Remove some global headers.

Removing:
- JniInvocation.h
- ScopedLocalFrame.h

Now that all usage is cleaned up.

libnativehelper now exports "include" as well so that
its headers can be cleaned up in the same way.

Test: none
Bug: 63762847
Change-Id: Iee8f59542dc1c80e2e262d2faf4eea829426a0d8