Misc fixes for -Wreorder:

1. Make it work correctly with anonymous unions.
2. Don't compute it if the warning isn't enabled.
3. Optimize the algorithm slightly to make it linear time in the 
case where we don't produce any warnings.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@76630 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed