[LLVMdev] Cleanup of constant sequence type construction

[Daniel Dunbar]

> What is the use of ConstantStruct without a type ?


This one already exists, it makes the type from the arguments. We don't
have the matching array version though.

> One suggestion, while you're here, add methods that use SmallVector  
> (IMO removing methods that use std::vector is a good idea).

Okay. Add seems like a safe start, remove is more volatile.

 - Daniel