Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with:		pfg
MFC After:		3 days
Sponsored by:		Netflix

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using mis-identified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

needed on ARM and PowerPC.

MFC after:	1 Week

o Add a MD header private to libc called _fpmath.h; this header
  contains bitfield layouts of MD floating-point types.
o Add a MI header private to libc called fpmath.h; this header
  contains bitfield layouts of MI floating-point types.
o Add private libc variables to lib/libc/$arch/gen/infinity.c for
  storing NaN values.
o Add __double_t and __float_t to <machine/_types.h>, and provide
  double_t and float_t typedefs in <math.h>.
o Add some C99 manifest constants (FP_ILOGB0, FP_ILOGBNAN, HUGE_VALF,
  HUGE_VALL, INFINITY, NAN, and return values for fpclassify()) to
  <math.h> and others (FLT_EVAL_METHOD, DECIMAL_DIG) to <float.h> via
  <machine/float.h>.
o Add C99 macro fpclassify() which calls __fpclassify{d,f,l}() based
  on the size of its argument.  __fpclassifyl() is never called on
  alpha because (sizeof(long double) == sizeof(double)), which is good
  since __fpclassifyl() can't deal with such a small `long double'.

This was developed by David Schultz and myself with input from bde and
fenner.

PR:		23103
Submitted by:	David Schultz <dschultz@uclink.Berkeley.EDU>
		(significant portions)
Reviewed by:	bde, fenner (earlier versions)