math/scilab: unbreak
- update dependency reference for textproc/saxon-he
- update some error handling stuff for libxml2 >= 2.13 API
- prevent picking up valgrind in ports builds with valgrind installed because that causes duplicate definition of the _start symbol in the final link at least on FreeBSD-14.3-RELEASE-p1 amd64.
- bump PORTREVISION and remove BROKEN
MFH: 2025Q3
(cherry picked from commit 7f5154b8b7147efcbb988aefbff43cc7c3d8aaa2)