Implement _ExtInt ABI for all ABIs in Clang, enable type for ABIs

This is the result of an audit of all of the ABIs in clang to implement
and enable the type for those targets.

Additionally, this finds an issue with integer-promotion passing for a
few platforms when using _ExtInt of < int, so this also corrects that
resulting in signext/zeroext being on a params of those types in some
platforms.

Differential Revisions: https://reviews.llvm.org/D79118