Further standards compliance fixes: export LONG_BIT, WORD_BIT, and 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.
Further standards compliance fixes: export LONG_BIT, WORD_BIT, and
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@

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars