Implement some accidentally missing vasm ops in llvm backend

Summary: cmpqi, srem, and bindaddr are all easy to do, I just forgot about them
in D1686955. Also add arm instructions to the big switch statement to get us
closer to removing the default case.

Reviewed By: @jasone

Differential Revision: D1694328

Signature: t1:1694328:1416513227:90da6cb341309d5c533d7864b059e2840b622be4
Don't print anything for gc() in set-save-twice.php

Summary: GC sometimes runs now so just ignore it.

Reviewed By: @alexmalyshev

Differential Revision: D1694501