ASYNCREAD in dmd driver (mars.d)

[b4s1L3]

I've just noticed some dead code (at least since self-hosting 
started, because otherwise git blame is not useful) in dmd's 
driver.

All the *static if* blocks that test the value of ASYNCREAD are 
dead.
Should they be removed or something ?

https://github.com/dlang/dmd/blame/32bb4ed7526b2bd622c0576734e5a6a6bd3c8278/src/ddmd/mars.d#L1361

although That's not much code.