If the basic block containing the BCCi64 (or BCCZi64) instruction ends with
an unconditional branch, that branch needs to be deleted before appending
the expansion of the BCCi64 to the end of the block.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122521 91177308-0d34-0410-b5e6-96231b3b80d8