Add support for timeconting in userland.

This diff exposes parts of clock_gettime(2) and gettimeofday(2) to
userland via libc eliberating processes from the need for a context
switch everytime they want to count the passage of time.

If a timecounter clock can be exposed to userland than it needs to set
its tc_user member to a non-zero value. Tested with one or multiple
counters per architecture.

The timing data is shared through a pointer found in the new ELF
auxiliary vector AUX_openbsd_timekeep containing timehands information
that is frequently updated by the kernel.

Timing differences between the last kernel update and the current time
are adjusted in userland by the tc_get_timecount() function inside the
MD usertc.c file.

This permits a much more responsive environment, quite visible in
browsers, office programs and gaming (apparently one is are able to fly
in Minecraft now).

Tested by robert@, sthen@, naddy@, kmos@, phessler@, and many others!

OK from at least kettenis@, cheloha@, naddy@, sthen@

Revert (leaving the complex math part alone). Some stuff is depending
on this historical behavior; so we're stuck in this stupid situation.
No cookie for me.

Move fabs(3), frexp(3), and modf(3) to libm--nothing has been using
them in libc for a very long time. OK guenther@.

remove from gen so that lint doesn't check gen if assembly versions
are available. spotted by theo

- ldexp implementation has issues. switch to the one from libm
- remove frexp in hppa64, cloned from hppa
- move generic ieee754 implementations of modf and ldexp to gen
ok kettenis@, "looks good" millert@

- move isinf, isnan dups to gen, since most is ieee 754
- is{inf,nan} should be macros for real-floating, so rename to
__is{inf,nan}, per C99
- implement C99 __fpclassify(), __fpclassifyf(), __isfinite(),
__isfinitef(), __isnormal(), __isnormalf(), __signbit(), __signbitf()
- long functions added, but not yet enabled, till ieee.h is fixed
- implement vax equivalents of the functions
- reimplement isinff, isnanf in a better way, and move to libc
- add qnan bytes for all archs
- bump major
man pages will follow
ok millert@. arm bits looked over by drahn@
discussed w/ theo, who showed the right direction, to put these
functions in libc

Move landisk to hardware floating point. At the moment the FPU context is
always saved upon context switches, as FPU registers are heavily used for
long long computations (don't ask). Gcc default to -m4.

Credits to drahn@ otto@ and deraadt@ for feedback and help testing.

Upgrade procedure if you don't want to use the damn snapshots:
- build and install new kernel, reboot off it
- build new gcc, do not install it yet
- make includes
- install new gcc
- build and install lib/csu and lib/libc
- make build

Move (back) to softfloat on sh for now.

and I forgot ldexp.c

build modf.c

branches: 1.1.1;
Initial revision

Revert (leaving the complex math part alone). Some stuff is depending
on this historical behavior; so we're stuck in this stupid situation.
No cookie for me.

Move fabs(3), frexp(3), and modf(3) to libm--nothing has been using
them in libc for a very long time. OK guenther@.

remove from gen so that lint doesn't check gen if assembly versions
are available. spotted by theo

- ldexp implementation has issues. switch to the one from libm
- remove frexp in hppa64, cloned from hppa
- move generic ieee754 implementations of modf and ldexp to gen
ok kettenis@, "looks good" millert@

- move isinf, isnan dups to gen, since most is ieee 754
- is{inf,nan} should be macros for real-floating, so rename to
__is{inf,nan}, per C99
- implement C99 __fpclassify(), __fpclassifyf(), __isfinite(),
__isfinitef(), __isnormal(), __isnormalf(), __signbit(), __signbitf()
- long functions added, but not yet enabled, till ieee.h is fixed
- implement vax equivalents of the functions
- reimplement isinff, isnanf in a better way, and move to libc
- add qnan bytes for all archs
- bump major
man pages will follow
ok millert@. arm bits looked over by drahn@
discussed w/ theo, who showed the right direction, to put these
functions in libc

Move landisk to hardware floating point. At the moment the FPU context is
always saved upon context switches, as FPU registers are heavily used for
long long computations (don't ask). Gcc default to -m4.

Credits to drahn@ otto@ and deraadt@ for feedback and help testing.

Upgrade procedure if you don't want to use the damn snapshots:
- build and install new kernel, reboot off it
- build new gcc, do not install it yet
- make includes
- install new gcc
- build and install lib/csu and lib/libc
- make build

Move (back) to softfloat on sh for now.

and I forgot ldexp.c

build modf.c

branches: 1.1.1;
Initial revision