Firefox 52 release contains unrelased NSPR changes

Unfortunately, Firefox 52 has been released with the following two changes to
NSPR, without having been released with NSPR yet:

(a) https://hg.mozilla.org/mozilla-central/diff/da9997b39928/nsprpub/pr/include/prio.h
(b) https://hg.mozilla.org/mozilla-central/diff/b70e2870aced/nsprpub/pr/src/md/windows/w32poll.c
  (context: https://bugzilla.mozilla.org/show_bug.cgi?id=1288308#c58 )

In addition, the same mistake was made for Firefox 54 (unreleased, currently in
alpha/aurora phase):

(c) https://hg.mozilla.org/mozilla-central/rev/9882b8c0d5fb
  (context: https://bugzilla.mozilla.org/show_bug.cgi?id=1331810#c4 )


We need to clean that up with a NSPR release, that has as little risks as
possible, because we should land it into Firefox 54, and potentially we might
want to uplift the same NSPR version into the earlier branches, like Firefox 53,
or even the long-lived Firefox 52 ESR branch.

Therefore I suggest that we release a NSPR 4.14 version, which is based on the
most recent release NSPR 4.13.1, plus the above changes, plus a completeness
change that Wan-Teh had suggested for (a/b).

I have already checked in those changes to a new NSPR 4.14 branch:
https://hg.mozilla.org/projects/nspr/graph


There's a remaining detail I'd like to discuss:

Commit (a) changed the size of PRNetAddr on Windows.
It would be easiest, if we could simply pick up that change.

However, is that change acceptable for NSPR?

Or is there anyone on Windows who ships NSPR binaries separately from
applications and requires forward compatibility? I guess that would only be a
concern, if an application allocated this structure, and passed it to the
library. Is this ever happening?

Kai