Restore the "GPL licensing not permitted" in GLUT license headers.

It was originally there but was removed erroneously. The emails in which
we received permission to relicense stated this restriction explicitly.

GLUT: Fix mistake in header license

* We felt that me adding this didn't really
properly communicate the spirit of the
email approval. You really can't just
'change' a license from MIT without author
approval... so this is superfluous.

GLUT: Relicense Mark Kilgard's GLUT components

* A copy of the email approving this change is
in the LICENSE.txt file
* This clears up several concerns
* We now have permission to clean / update GLUT
code and redistrubute its binaries.
* We have to ensure all of Mark's work is *not*
GPL licensed as per his wishes.

Break glut out from mesa lib

As glut is no longer in upstream Mesa and no longer developed
we will need to keep a fork.

GLUT: Fix mistake in header license

* We felt that me adding this didn't really
properly communicate the spirit of the
email approval. You really can't just
'change' a license from MIT without author
approval... so this is superfluous.

GLUT: Relicense Mark Kilgard's GLUT components

* A copy of the email approving this change is
in the LICENSE.txt file
* This clears up several concerns
* We now have permission to clean / update GLUT
code and redistrubute its binaries.
* We have to ensure all of Mark's work is *not*
GPL licensed as per his wishes.

Break glut out from mesa lib

As glut is no longer in upstream Mesa and no longer developed
we will need to keep a fork.