unwind: remove a could of extraneous `else` (NFC)
unwind: remove a could of extraneous `else` (NFC)

Simplify `if return else return` by removing the unnecessary `else`.

git-svn-id: 62ef012455b6b8fcec9c41ca270ebf409aae1006@372233 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/libunwind,llvm-mirror/libunwind,llvm-mirror/libunwind