lib/58846: librt exports __rt_cerror on some architectures but not others

[campbell+netbsd%mumble.net@localhost]

>Number:         58846
>Category:       lib
>Synopsis:       librt exports __rt_cerror on some architectures but not others
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    lib-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Nov 22 16:15:01 +0000 2024
>Originator:     Taylor R Campbell
>Release:        current, 10, 9, ...
>Organization:
The NetRT __found_error
>Environment:
>Description:
On amd64, librt exports __rt_cerror.

On earmv7hf, librt does not export __rt_cerror.

If this is intentional, need to deal with MD expected symbol lists.

If this is not intentional, need to diagnose why and fix it.

Probably related to:

PR lib/58845: libposix exports __posix_cerror on some architectures but not others
>How-To-Repeat:
build with an MI expected symbols list
>Fix:
Yes, please!