Remove obsolete constants in version 1.0.0

[asomers]

This issue tracks constants that should be removed from libc for release 1.0.0.

The following are absent in FreeBSD 11, never had stable values across versions, and should never have been used by third party software. They should be removed from FreeBSD.

CTL_MAXID
KERN_MAXID
HW_MAXID
USER_MAXID

The following is still present in FreeBSD 11, but like the previous four it should never have been used by third party software, and its value isn't guaranteed to be stable across versions. It should be removed from FreeBSD
CTL_P1003_1B_MAXID

[asomers]

Add to the list AIO_LISTIO_MAX. That symbol should never be used because the quantity it represents can potentially vary at runtime. Programs should use sysconf(3) instead.

[gnzlbg]

I've deprecated these on master, and they are also doc(hidden). I'd say that we'd remove them in one of the next releases.

[asomers]

I agree.

[gnzlbg]

Feel free to open a PR removing these.