- libpluto was earlier under LGPL - it used to also depend on polylib
  (which is itself under GPL). It now only depends on piplib and isl,
  which are under LGPL and MIT licenses resp. As a result, libpluto
  can be made available under the MIT license.

Signed-off-by: Uday Bondhugula <udayb@iisc.ac.in>