Switch from <sys/endian.h> or <machine/endian.h> to the new,
being-standardized <endian.h>

ok deraadt@ millert@ beck@

Let this compile with gcc 2.

- 80-bit and quad precision trigonometric and other most
important functions: acosl, asinl, atanl, atan2l, cosl,
sinl, tanl, exp2l, frexpl, ilogbl, ldexpl, logbl, scalbnl,
fabsl, hypotl, powl, sqrtl, rintl, copysignl, nanl, fdiml,
fmaxl, fminl. mostly taken from freebsd, needed alot of
changes to adapt. note, these are all c versions; and are
quite slow when architectures have, e.g. sqrt. assembly
versions will be added afterwards
- make them .weak/__weak_alias to the double precision
versions on other archs
- no need to have two finites. finite() and finitef() are
non-standard 3BSD obsolete versions of isfinite. remove
from libm. make them weak_alias in libc to __isfinite and
__isfinitef instead. similarly make 3BSD obsolete versions
of isinf, isinff, isnan, isnanf weak_aliases to C99's
__isinf, __isinff, __isnan, __isnanf
- remove unused infinity.c. the c library has infinities
for each supported platform
- use STRICT_ASSIGN cast hack for _kernel_rem_pio2, so that
the double version has a chance of working on i386 with
extra precision
- avoid storing multiple copies of the pi/2 array, since
it won't vary
- bump major due to removed finite/finitef. although they
will be in libc, which anything is linked to, minor bump
might be enough
ok millert@. tested by sthen@, jsg@, ajacoutot@, kili@, naddy@