Oilpan: Handle a case where mmap returns MAP_FAILED

mmap can return MAP_FAILED in some unlucky cases (e.g., a specified address was too large etc).
This CL adds a logic to handle a case where mmap returns MAP_FAILED.
Specifically, this CL tries mmap at most 10 times until mmap succeeds.

BUG=429911

Review URL: https://codereview.chromium.org/682993007

git-svn-id: svn://svn.chromium.org/blink/trunk@185028 bbb929c8-8fbe-4397-9dbb-9b2b20218538