bldinstallercommon: extract_file eats output by default

Modified extract_file to eat the output by default. If output is needed
in calling script, it can be retrieved by switching 3rd parameter to
True (now windows only).

Change-Id: Icd312843cb35aebefeb7abbcb02d6c13247598c4
Reviewed-by: Iikka Eklund <iikka.eklund@digia.com>