[BlackBerry] Implement OSAllocator::commit/decommit in the correct way

[BlackBerry] Implement OSAllocator::commit/decommit in the correct way
https://bugs.webkit.org/show_bug.cgi?id=77013

We should use mmap(PROT_NONE, MAP_LAZY) instead of posix_madvise() to
implement memory decommitting for QNX.

Patch by Yong Li <yoli@rim.com> on 2012-03-19
Reviewed by Rob Buis.

* wtf/OSAllocatorPosix.cpp:
(WTF::OSAllocator::reserveUncommitted):
(WTF::OSAllocator::commit):
(WTF::OSAllocator::decommit):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@111234 268f45cc-cd09-0410-ab3c-d52691b4dbfc