Fix UB in bool packetmath test.
It's UB to explicitly load 0xFF into a bool for the select mask. Changing the mask to use valid boolean values causes pselect to fail, since the intel blend intrinsic checks the high bit instead of the low bit.
It's UB to explicitly load 0xFF into a bool for the select mask. Changing the mask to use valid boolean values causes pselect to fail, since the intel blend intrinsic checks the high bit instead of the low bit.