Change UnwindLLDB::SearchForSavedLocationForRegister so that it will allow for
the link register save location being in the link register - in which case we
should iterate down the stack, not recursively try to find the lr in the current
frame over and over.

<rdar://problem/13932954>


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@183282 91177308-0d34-0410-b5e6-96231b3b80d8