fix #Q101 - score file bullet proofing

fix #Q101 - score file bullet proofing

     Guard against buffer overflows when reading in score entries, in case
`record' has become corrupted or been maliciously modified.  This addresses
the part of "#Q101: Security bug in nethack 3.4.3" that we have control
over.  A Gentoo bug tracking discussion pointed out to us by <email deleted>, describes how that particular Linux
distribution makes users be members of the games group, allowing them to
modify files in nethack's playground directory when it has been set up in
the usual ``setgid games'' manner, thus making score processing in that
environment be vulnerable to buffer overrun exploits.