ANDROID: vendor_hooks: Add hooks for reducing virtual address fragmentation

When running 32-bit apps for a long time, virtual address becomes fragmented which can lead to allocation failures when a large virtually-contiguous area is requested.
Add hooks to implement pools to cluster together small-sized virtual address mappings.
Add hooks to implement reserved virtual address zone with usage restrictions controlled by vendor hooks.
These hooks help in controlling virtual address space fragmentation.

Bug: 187259935

Signed-off-by: xieliujie <xieliujie@oppo.com>
Change-Id: I48c057041f9c7b8c5ab0af305f0cd87a039d0447