Improve -Wuninitialized to take into account field ordering with initializer
lists.  Since the fields are inititalized one at a time, using a field with
lower index to initialize a higher indexed field should not be warned on.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@218339 91177308-0d34-0410-b5e6-96231b3b80d8