patch: don't issue -Wreorder warnings when order doesn't matter

[Joern Rennecke]

Quoting Daniel Marjamäki <daniel.marjamaki@gmail.com>:

> Yes. It sounds unlikely. But not impossible of course. I could also
> make sure the member variables are POD types before I inhibit the
> warning. I just have no idea how I check if a member is POD. But I
> could investigate this.

You could check if it has a constructor, using
TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (field))