Add precompiled hash only when policy exists

precompiled_system_ext_and_mapping.sha256 and
precompiled_product_and_mapping.sha256 has been installed, regardless of
existence of system_ext and product policies. This change only installs
such hash files when policy files exist, for consistency.

Bug: 186727553
Test: boot yukawa and see precompiled sepolicy is used
Change-Id: Iaad827cefdbe82e68288cd6cc59b55b5f28c229d
1 file changed