Update MASTER_SITES
Approved by: jmz
changed distfile from calc-2.9.3t6.tar.gz to calc-2.9.3t6.tar calc is fetched as an on-the-fly tarball from ftp.cdrom.com gzipped on-the-fly tars are not supported. removed trailing whitespace on several lines in PLIST revised DESCR to <24 lines.