upset now understands 'external-source' option

[Christopher Faylor]

I've added the previously mentioned external-source option to
upset, so this is now valid in setup.hint (but not setup.ini).

  @ libbz2
  sdesc: "shared libraries for bzip2 (runtime)"
  ldesc: "bzip2 is a freely available, patent free, high-quality data
  compressor. It typically compresses files to within 10% to 15% of the best
  available techniques (the PPM family of statistical compressors), whilst being
  around twice as fast at compression and six times faster at decompression."
  category: Libs 
  requires: cygwin bzip2
  external-source: bzip2

Anyone want to submit the corresponding web page change?

FYI,
cgf