Redefine the io provider using the SDT(9) macros instead of doing everything
manually. This change has no functional impact.

Discussed with:	gnn
Be more selective when filtering for lib*.so.N files.  These are deleted
at the end of the upgrade process, after warning users to upgrade any
3rd party software (e.g., from the ports tree) which might link to the
libraries being removed.

Prior to this commit, the line
  /usr/lib/libc.so|...|/lib/libc.so.7
matched the regex, which -- upgrading from 9.x to 10.x, where libc.so is
a regular file and thus was not part of a line which matched the regex --
resulted in freebsd-update thinking that /usr/lib/libc.so was a shared
library which was being removed as part of the upgrade.  This had some
unfortunate consequences.

This will be part of an upcoming Errata Notice.
Fix crossed fingers output. Only comment changed.
Add support for using "pkg+http://" for the PACKAGESITE.

pkg 1.2 is adding this support as well. This should help
lessen the confusion on why the default SRV PACKAGESITE
does not load in a browser.

Adapated from:	matthew's upstream pkg change
Approved by:	bapt
MFC after:	2 days
Some microoptimizations for da and ada drivers:
 - Replace ordered_tag_count counter with single flag;
 - From da remove outstanding_cmds counter, duplicating pending_ccbs list;
 - From da_softc remove unused links field.
interrupt-parent and #interrupt-cells are written to the tree using
encode-int.
Revert r256921 to prevent error output when in the wrong directory.
This should have been reverted with the stable/10/Makefile.inc1
revert, but apparently my commit did not go through.

Discussed with:	cperciva (originally)
Regenerate documentation post r256915:

Stop conflating WITHOUT_CLANG with WITHOUT_CLANG_IS_CC.  This allows
bootstrapping a copy of clang without building clang for the base system
which is useful for nanobsd and similar setups.  It's still probably
wrong to conflate what is installed as /usr/bin/cc with the selection
of a bootstrap compiler under WITH*_CLANG_IS_CC, but that's for another
day.