/usr/Makefile: Add pkg-bootstrap target

New snapshots provide a pre-built "pkg" tool so pre-build dports
binaries can be installed easily.  However, upgrades from older releases
won't have "pkg" available, and for those systems they had to download
the entire dports repository just to build pkg in order to take advantage
of the available pre-built packages.

To fix this situation, and the situation where /usr/local/sbin/pkg is
lost for any reason, a new make target has been added to /usr/Makefile:
pkg-bootstrap

The pkg-bootstrap target will download a pre-built "pkg-static" program
along with pkg.conf and all the man pages.  In reality, pkg-static is
only used for one command, and that is to install a full "pkg" program
from the dragonfly repository.

If "pkg.conf" already exists, a message will instruct the user to move
it first.  If /usr/local/sbin/pkg already exists, the target won't work
and it won't even show as an option.

After pkg-static is installed, the user will be instructed to type
"rehash; pkg-static install -y pkg; rehash" which should result in the
system having the latest pkg on their system and thus can proceed to
install packages normally.
Merge branch 'master' into gsocdrm_merger
kernel - Increase IFQ_MAXLEN from 50 to 250

* IFQ_MAXLEN is used as the default for numerous pseudo-network drivers.
  The value 50 is just too low.  Increase to 250.
kernel - Fix several bugs in FAIRQ

* Fix several possible overflows due to high-valued machclk_freq constants
  and uint's that should have been uint64's.  Among other things this fixes
  bandwidth calculations that could previously get into weird states.

* Refactor the fairq_selectq() routine to fix numerous cases where the
  head of the queue could get advanced multiple times without pulling a
  packet off the queue, causing packets in queues to be excessively
  delayed.

Both of these were rather serious issues.  Operation is far smoother with
the bugs fixed.
<sys/cdefs.h>: Add some macros needed for our <tgmath.h>.

Taken-from: FreeBSD
gcc: Stop installing GCC's tgmath.h to /usr/libdata/gcc{44,47}.

Before this commit, the recently imported <tgmath.h> (in
/usr/include when installed) wasn't taken because of GCC's
own copies in /usr/libdata/gcc{44,47}, which comes first
in the compiler's internal include search path.

Since it is a standard header, we want our version to be
taken, so stop installing GCC's version and remove it via
'make upgrade'.

There are no other standard headers in /usr/libdata/gcc{44,47}.
gcc44: Bring back an accidentally removed file.
<sys/cdefs.h>: Bring in a compatibility macro for C11's _Static_assert.

Apparently gcc47 has support outside of C11, but for processing our
<complex.h> with gcc44, this is necessary.

Taken-from: FreeBSD
Merge branch 'master' into gsocdrm_jfree