cad/ngspice_rework: update to v41

The current version's distfiles have dropped off sourceforge, so let's
take this time to update. While we're here, upstream has since removed
the sbrk usage, so we can successfully build on aarch64 again.

Reverse dependencies PORTREVISION bumped to play it safe, because it's
not clear to me that the ABI really didn't change.

Approved by: kevinz5000@gmail.com (maintainer)