htdigest: Fix buffer overflow when reading digest password file with very long lines.
Backport of r1475878 from trunk resp. r147…
htdigest: Fix buffer overflow when reading digestpassword file with very long lines.PR 54893.Backport of r1475878 from trunk resp.r1476089 from 2.4.x resp. r1476242from 2.2.x.Proposed/Backported by: rjungReviewed by: minfrin, wrowe