Store native libs aligned to PAGE_SIZE

- Add a new flag to zipalign (-p) that page aligns shared
  libraries (zip entries ending with ".so") in the archive.

- Add a new build variable LOCAL_PAGE_ALIGN_SHARED_LIBRARIES
  to turn on this behaviour in zipalign.

- Add a new LOCAL_JNI_SHARED_LIBRARIES_ZIP_OPTIONS to control
  zip behaviour.

Bug: 8076853
Bug: 19330157

Co-Authored-By: Simon Baldwin <simonb@google.com>
Co-Authored-By: Dimitry Ivanov <dimitry@google.com>
Change-Id: I1aa2c039bb2a590ae72f256acc9ba5401c2c59b1