standards/58603: getentropy(3): update visibility and documentation for POSIX.1-2024

[campbell+netbsd%mumble.net@localhost]

>Number:         58603
>Category:       standards
>Synopsis:       getentropy(3): update visibility and documentation for POSIX.1-2024
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    standards-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Aug 15 23:20:00 +0000 2024
>Originator:     Taylor R Campbell
>Release:        current, 10
>Organization:
The NentropyBSD.1-2024 Foundation
>Environment:
>Description:
getentropy(3) is now in POSIX.1-2024:

https://pubs.opengroup.org/onlinepubs/9799919799.2024edition/functions/getentropy.html

Its declaration, and the definition of GETENTROPY_MAX, should be made visible in header files if _POSIX_C_SOURCE >= 202405L or _XOPEN_SOURCE >= 800, and the man page should cite POSIX.1-2024.
>How-To-Repeat:
cod inspection
>Fix:
Yes, please!