ports build tested by espie@

defines.
ok deraadt@ millert@

NL_{ARG,LANG,MSG,SET,TEXT}MAX with newer POSIX.
Hide {FLT,DBL}_{DIG,MAX,MIN} and {PASS,TMP,NL_N}_MAX with newer XPG.
Make _POSIX_NGROUPS_MAX and _POSIX_OPEN_MAX conditional on the POSIX
version, like _POSIX_TZNAME_MAX already is.
Add some more _POSIX_* and _XOPEN_* 'specified' limits.
ok kettenis@

ok millert@

ok krw@, laurent@

Use correct values for _POSIX_TTY_NAME_MAX and _POSIX_LOGIN_NAME_MAX
Define MAXLOGNAME in terms of LOGIN_NAME_MAX
OK krw@

in sys/cdefs.h) instead of _FOO_SOURCE.  Also fix several namespace
pollution issues, including the byte order defines.  OK deraadt@

should only be 255.  You would think they would be the same but you'd be
wrong.

respectively instead of duplicating their values.

o _POSIX_CHILD_MAX increased to 25
o _POSIX2_RE_DUP_MAX renamed _POSIX_RE_DUP_MAX
o _POSIX_SYMLINK_MAX and SYMLINK_MAX added (same as PATH_MAX)
o _POSIX_SYMLOOP_MAX and SYMLOOP_MAX added (like MAXSYMLINKS)

rescinded 22 July 1999.  Proofed by myself and Theo.

type characteristics.
internal_types.h will contain only settings invisible from standard C, e.g.,
in the __* or _[A-Z]* namespace, and be reused by files like limits.h.
This allows us to shorten machine/limits.h greatly, as all the common defines
are now in sys/limits.h, plus a small stub in internal_types.h.
Tested on all arches as far as I know.
Approved after discussion with art, millert, deraadt, and others.

All POSIX libc api now there (to P1003.1c/D10)
(more md stuff is needed for other libc/arch/*)
(setlogin is no longer a special syscall)
Add -pthread option to gcc (that makes it use -lc_r and -D_POSIX_THREADS).
Doc some re-entrant routines
Add libc_r to intro(3)
dig() uses some libc srcs and an extra -I was needed there.
Add more md stuff to libc_r.
Update includes for the pthreads api
Update libc_r TODO

entire trees for testing anyway, I might as well do this intrusive touching
of include files now.  Added openBSD tags.

Correct _POSIX_ARG_MAX; it should define the minimum allowed argument size,
not the supported on (we have sysconf for that)