- Add target lowering methods to get the preferred format for the FDE and LSDA

- Add target lowering methods to get the preferred format for the FDE and LSDA
  encodings.
- Make some of the values emitted by the FDEs dependent upon the pointer
  size. This is in line with how GCC does things. And it has the benefit of
  working for Darwin in 64-bit mode now.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80428 91177308-0d34-0410-b5e6-96231b3b80d8