Revert to first-best-fit run/chunk allocation.

This effectively reverts 97c04a93838c4001688fe31bf018972b4696efe2 (Use
first-fit rather than first-best-fit run/chunk allocation.).  In some
pathological cases, first-fit search dominates allocation time, and it
also tends not to converge as readily on a steady state of memory
layout, since precise allocation order has a bigger effect than for

(cherry picked from upstream commit

Bug: 22172059
(cherry picked from commit 486fa41f4ace88a9d1b96831bc36cbd2cfa4957e)

Change-Id: I88f7b5bc3b18c953cc9ad8ce4a54c5a0c582c613
3 files changed