[BranchFolding] Remove dead code for handling EHPad blocks

Summary: This code tries to handle the case where IBB is an EHPad, but there's an earlier check that uses PBB->hasEHPadSuccessor(). Where PBB is a predecessor of IBB. The hasEHPadSuccessor function would have visited IBB and seen that it was an EHPad and returned false. This would prevent us from reaching this code with IBB as an EHPad.

Looks like this code was originally added in rL37427 (ancient) and made dead in rL143001.

Reviewers: rnk, void, efriedma

Reviewed By: rnk

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D57358

llvm-svn: 353375