Change ambiguous uses of term 'funclet' to 'EH scopes'. NFC.

Summary:
`getEHScopeMembership()` function is used not only for funclet-based
EHs; they apply to all EH schemes that use the scoped IR
(catchpad/cleanuppad/...). D47005 (rL333045) changed some of the uses of
the term 'funclet' to 'EH scopes' in case they apply to all scoped EH,
and this fixes more of them. For `FuncletLayout` pass, I left it as is
because the pass is only used for funclet-based EH.

Reviewers: majnemer

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D47611

llvm-svn: 333711