Low Signed/multiplyFullWidth(by:) sign #102
Description
I discovered with (#99) that the low sign, formed by Signed/multiplyFullWidth(by:), is inconsistent with every other multiplication operation. I remember thinking that the low part should be positive, because that's how the (high: T, low: T.Magnitude) pattern works. Well, I was wrong. The low and high sign should match, in order for the following operations to yield the same result:
*,*=,&*,&*=multiplyFullWidth(by:)multipliedFullWidth(by:)multiplyReportingOverflow(by:)multipliedReportingOverflow(by:)