To avoid any issues calling malloc related routines, use mmap/munmap.
Specifically, this avoids any problems when this is compiled into a
malloc debug shared library.
(cherry picked from commit 6425327c3278137d153b8a7505f97d2f5f058d49)
Change-Id: If43d12b2c588c9abcbfbbd2c53702cdac7695a73