log2l() missing

[Thomas Klausner <wiz%NetBSD.org@localhost>]

Hi!

py-numpy can't be updated to 1.24.x because it wants to use log2l()
but NetBSD doesn't provide it.

Even worse, the definition even exists in /usr/include/math.h, so a
configure check that only looks in the headers might find that.

I found
http://gnats.netbsd.org/cgi-bin/query-pr-single.pl?number=53234 from
2018 on this.

Can someone please add these?

Thanks,
 Thomas