trailing whitespace flag day

[Colin Walters]

Hi,

Some patch submitters feel strongly about trailing whitespace, and the
two options I see were to either have a flag day for it, or just do it
incrementally (i.e. only strip whitespace from areas modified by a
patch).

Since we don't have many branches with potentially conflicting
features around, I thought we'd just do a flag day.  The major
downside of this is that "git annotate" becomes less useful, but I
could imagine an annotate feature that goes for the last
non-whitespace change.

If you've committed to dbus (or have some actual stake), feel free to
comment if you have a strong feeling for or against.   I have a patch
sitting here to do the flag day, and hopefully we can get some of e.g.
Lennart's patches in after they're rebased on this.