Re-apply r201292.  We're not going to enforce proper stack frame alignment on i386/x86_64
because there are too many trap handlers that will have an improperly aligned caller sp 
and this will cause the unwinder to stop too early.  


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@201637 91177308-0d34-0410-b5e6-96231b3b80d8