QtBase: Let's use the by default make tool for qtbase as well

Change-Id: Ibd1857ce5c2bbcb2bc0177f337dfe945c0675eec
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Tony Sarajärvi <tony.sarajarvi@digia.com>
Reviewed-by: Simo Fält <simo.falt@digia.com>