Make HAVE_MADV_FREE, HAVE_MADV_FREE_REUSE and HAVE_VIRTUALALLOC local macros as it only used in wtf/TCSystemAlloc.h .

HAVE_VIRTUALALLOC is compeletely removed per abarth comment: https://codereview.chromium.org/22661006/#msg5

BUG=

Review URL: https://chromiumcodereview.appspot.com/22661006

git-svn-id: svn://svn.chromium.org/blink/trunk@156423 bbb929c8-8fbe-4397-9dbb-9b2b20218538