CachedAppOptimizer: Remove PAGE_MASK usage

Android V will support page size agnostic targets. The bionic macro
PAGE_MASK won't be defined for the agnostic targets. For the CachedAppOptimizer,
the PAGE_MASK macro will be replaced by ~(getpagesize() - 1).

Bug: 296512786
Test: source build/envsetup.sh
      lunch aosp_cf_arm64_phone_pgagnostic
      m
Change-Id: Ic4c50dcb5e4eb4a8ce6460df240340868c76f252