pthread_testcancel(3): Update list of cancellation points.

This should be a fairly complete list of cancellation points in libc, libthr
and librt, including standard as well as non-standard functions.
Merge latest NetBSD changes.
This adds some new NetBSD releases and makes some simple formatting changes.

With this commit NetBSD and FreeBSD should have identical files.
DragonflyFBSD has the version immediately prior to this commit.

When committing to this file please try to coordinate with all three groups.

Submitted by:	Alan Barrett <apb@cequrux.com>