Intrinsic mangling and typeless pointers

[Rafael Espíndola via llvm-commits]

We have hit https://llvm.org/bugs/show_bug.cgi?id=30509 while LTOing
some internal project, so I decided to at least familiarize myself
with the issue.

The bug is about the fact that a type renaming causes an intrinsic to
be recreated, but that got me thinking why we do need to mangle the
intrinsic names? Any information we could want is available from the
type itself.

This is particularly troublesome for typeless pointers as they require
us to not look a the element type. Could we just mangle all pointer
types as 'p'?

Cheers,
Rafael