Clean up #includes in `hidden_api.h`.

Move one template function `ShouldDenyAccessToMember()` to
the .cc file and reduce the amount of code included by .h.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Change-Id: Ic969902cd0fa3b57e11eb9d8a8413f4f71a6d28b
2 files changed