Add product_available to product available modules

vendor_available modules were available to product modules.
However, not all vendor_available modules are required to be
available to product modules. Some modules want to be available only
to product modules but not vendor modules.

To cover the requirement, we separate product_available from
vendor_available.
vendor_available will not provide product available module.

Rename libcutils/include_vndk to libcutils/include_outside_system as
it provides the headers to the modules outside the system partition
including /product.

Bug: 150902910
Test: build
Change-Id: I791b5a6a1dc99442065debfce6fa0f54a335fcea