www/librespeed: Update to 5.2.4

While here pet portfmt.

Changes: https://github.com/librespeed/speedtest/releases/tag/5.2.4
PR: 254589
Submitted by: Dries Michiels <driesm.michiels@gmail.com> (maintainer)
Approved by: tcberner (mentor)
Differential Revision: https://reviews.freebsd.org/D29445