lib/52541: ldexpl() missing from NetBSD 6

[gem%rellim.com@localhost]

>Number:         52541
>Category:       lib
>Synopsis:       ldexpl()  missing from NetBSD 6
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    lib-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Sep 14 19:05:00 +0000 2017
>Originator:     Gary E. Miller
>Release:        NetBSD 6
>Organization:
rellim
>Environment:
>Description:
ISO C99 and POSIX 2001 specify ldexpl().

ldexpl() is not in NetBSD 6.  It is in NetBSD 7.

The prevents recent versions of NTPsec from building on NetBSD 6.
>How-To-Repeat:
Just look for the man page:

man ldexpl

Not there.
>Fix:
Backport NetBSD 7 math.h and ldexpl() to NetBSD 6.