Fix build ID parsing logic in stable trees

hi, sending fix for buildid parsing that affects only stable trees after merging upstream fix [1].

Upstream then factored out the whole buildid parsing code, so it does not have the problem.

I'm sending the fix for affected longterm trees 5.15 6.1 6.6 6.11.

thanks, jirka

[1] 905415ff3ffb ("lib/buildid: harden build ID parsing logic")