graphics/openexr*: update to 3.4.16 bugfix release

"v3.4.16 fixes a bug which created unreadable DWAB files in certain
circumstances. There is also a fix to prevent 'undefined behavior'
warnings with the BytesAttribute"

Changelog: https://github.com/AcademySoftwareFoundation/openexr/releases/tag/v3.4.16
PR: 299085
Pull request: https://github.com/freebsd/freebsd-ports/pull/631
MFH: 2026Q4