Originally I thought interleaving AIR with MIR will be useful, however
as it stands, I have used it very sporadically, and recently, not at
all, and I do not think anyone else is actually using it. If there is
a simple error such as a wrong instruction emitted,
`objdump` is perfectly capable of narrowing it down, while if there's
something more subtle happening, regardless of having `--verbose-mir`
functionality or not, you still gotta go via the debugger which
offers a better view at interleaved source program with the emitted
machine code. Finally, I believe `-femit-asm` when we add it will offer a
more generic substitute.