Avoid sign-extension when extracting the low bits of addresses when checking if the addresses are 4-byte aligned.
Avoid sign-extension when extracting the low bits of addresses when checking
if the addresses are 4-byte aligned.

ok jsing@

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars