split IrInstruction into IrInst, IrInstSrc, IrInstGen

This makes it so that less memory is used for IR instructions, as well
as catching bugs when one expected one kind of instruction and received
the other.
6aac423964Andrew Kelley committed on 1/26/2020, 2:49:32 AMparent357f42d
9 files changedLine totals unavailable