Log Message:
Various updates and fixes that I've collected recently:

	* Provide nanosleep(2) and usleep(3) wrappers.

	* Make sure sigprocmask syscalls are used in pth_system.

	* "Fix" FD_SET handling in the select(2) wrapper so that
	  mismatches between pth FD_SETSIZE and user program
	  FD_SETSIZE don't cause problems.

	* Update poll(2) wrapper to be more poll(2) like - in
          particular never return EINVAL for bad file descriptors
	  Thanks to Matthias Drochner for this.

	* Improve error handling in connect(2) wrapper so that we
	  don't confuse the scheduler. This fixes pkg/17944 from
	  Christian Biere (ChristianBiere at gmx dot de)

	* Introduce autoconf handling of the value of FD_SETSIZE
	  used by pth. If we have to hard code a value we might
	  as well make it easy to change and make the inclusion
	  of pth.h or pthread.h by a program that re-defines
	  FD_SETSIZE an error.

	  Inspired by pkg/17944.

	* Fix a compiler warning that I introduced a little while
	  ago.

	* Disable --enable-syscall-hard for non-NetBSD platforms
	  and for pre-1.6/m68k. Make a note of the PRs that need
	  fixing. This closes pkg/18236 from Klaus Heinz (k dot
	  heinz dot sep dot zwei at onlinehome dot de)

The FD_SETSIZE problems would be handled better if pth was changed
to use poll(2), and not select(2), internally.