'RELENG_5_3_0_RELEASE'.

This commit was manufactured to restore the state of the 5.3-RELEASE image.

Prodded by:	ru

*are* in libc for historical reasons, but programmers should not rely
on that fact.

Also remove a BUGS section that is not relevant here.

  isnormal().  The current isinf() and isnan() are perserved for
  binary compatibility with 5.0, but new programs will use the macros.
o Implement C99 comparison macros isgreater(), isgreaterequal(),
  isless(), islessequal(), islessgreater(), isunordered().

Submitted by:	David Schultz <dschultz@uclink.Berkeley.EDU>

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)