[BlackBerry] Enable USE_SYSTEM_MALLOC by default
https://bugs.webkit.org/show_bug.cgi?id=112365

Patch by Alberto Garcia <agarcia@igalia.com> on 2013-03-19
Reviewed by Benjamin Poulain.

Enable USE_SYSTEM_MALLOC by default via FeatureList.pm instead of
harcoding it in wtf/Platform.h

Source/WTF:

* wtf/Platform.h:

Tools:

* Scripts/webkitperl/FeatureList.pm:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146222 268f45cc-cd09-0410-ab3c-d52691b4dbfc