ld80/s_expl.c:

* Update the evaluation of the polynomial.  This allows the removal
  of the now unused variables t23 and t45.

ld128/s_expl.c:

* Update the evaluation of the polynomial and the intermediate
  result t.  This update allows several numerical constants to be
  written as double rather than long double constants.   Update
  the constants as appropriate.

Obtained from:	bde
ld80/s_expl.c:

* In the special case x = -Inf or -NaN, use a micro-optimization
  to eliminate the need to access u.xbits.man.

* Fix an off-by-one for small arguments |x| < 0x1p-65.

ld128/s_expl.c:

* In the special case x = -Inf or -NaN, use a micro-optimization
  to eliminate the need to access u.xbits.manh and u.xbits.manl.

* Fix an off-by-one for small arguments |x| < 0x1p-114.

Obtained from:	bde
ext2fs: Update Block Group Descriptor struct.

Uncover some, previously reserved, fields that are used by Ext4.
These are currently unused but it is good to have them for future
reference.

Reviewed by:	bde
MFC after:	3 days
Add a comment to note that bde supplied most, if not all,
of the optimizations.
Micro-optimization: move the unary mius operator to operate
on a literal constant.

Obtained from:	bde
ld80/s_expl.c:

* Use integral numerical constants, and let the compiler do the
  conversion to long double.

ld128/s_expl.c:

* Use integral numerical constants, and let the compiler do the
  conversion to long double.
* Use the ENTERI/RETURNI macros, which are no-ops on ld128.  This
  however makes the ld80 and ld128 identical.

Reviewed by:	bde (as part of larger diff)
Fix receive on the AR9285 (Kite) with only one antenna connected.

The main problem here is that fast and driver RX diversity isn't actually
configured; I need to figure out why that is.  That said, this makes
the single-antenna connected AR9285 and AR2427 (AR9285 w/ no 11n) work
correctly.

PR:		kern/179269