Purge default locations from commonly used device makespecs

Including /usr/include and lib can cause cryptic failures if there is
already a Qt installed to /usr.

Having standard locations listed should not be necessary at all.

Change-Id: I08a15a064cc1aec126733f7e1962a2fa2ec38fcb
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Andy Nichols <andy.nichols@theqtcompany.com>