Avoid permitted_packages related build failures in unbundled builds

Unbundled builds cause AlwaysUsePrebuiltSdks() to return true which
causes java_sdk_library_import modules to be preferred instead of their
corresponding java_sdk_library module. That causes the
platform-bootclasspath module to depend on prebuilt versions of modules
like framework-statsd which currently do not specify
permitted_packages and so cause a failure.

This is a temporary hack to prevent an unbundled build from checking
for permitted_packages. It can be removed once the prebuilts have been
updated to include the permitted_packages.

Bug: 193095050
Bug: 193889859
Test: m TARGET_BUILD_APPS=Calendar apps_only
      - before the change it failed in Soong.
      - after the change it started failing, later in Make, so the
        Soong problem has been worked around.
      - I reverted all the recent changes to permitted_packages and
        ran this and it still failed so that failure is unrelated to
        these changes.
Change-Id: I213d35437d76d61cf616d1f16dae213b311c6c8e