* exclude ICECC_PARALLEL_MAKE (like PARALLEL_MAKE is)
* add ICECC_DISBLED to be able to disable whole icecc functionality
while keeping icecc enabled. This is useful when you want multiple
builders sharing same sstate-cache, but only some of them using icecc.
* inheriting icecc changes all checksums because of do_*_prepends calls,
but because icecc should not influence binary output of task we should
get same checksums for tasks build with and without icecc
* ICECC_DISABLED when set (to any non-empty value will disable icecc env
modifications but while keeping same sstate checksum
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com> Signed-off-by: Saul Wold <sgw@linux.intel.com>
