buildroot

gcc-final: things are no longer installed in $(HOST_DIR)/usr

Since things are no longer installed in $(HOST_DIR)/usr, the callers
should also not refer to it.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Reviewed-by: Romain Naour <romain.naour@smile.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>