libsparse: support using old mmap instead of bionic's mmap

Summary:
Setting BOARD_NEEDS_OLD_MMAP is the same as reverting commit fccfa414c96061689676a8803e3492f992618486: "libsparse: Use BIONIC implementation of mmap64()"

The correct bionic mmap64 implementation causes issues on some htc8960 devices.

Depends on D214

Test Plan: verified by jriordan001 prior to flag, will need to add to the htc 8960 common tree.

Reviewers: randall.rushing, anders3408, raymanfx, jriordan001

Reviewed By: jriordan001

Differential Revision: http://review.codefirex.com/D213