Bug#564474: mesa: glut files have non-DFSG-free license

[Sam Geeraerts <samgee@elmundolibre.be>]

Kilgard's "Yes, that's fine" reply for bug #131997 only applies to that 
package, not to all of his code with that same license notice. Both 
pointblast.c and spriteblast.c are not in that package, so they still 
fall under the original (unclarified) non-DFSG-free license. See the 
FSF's statement I quoted earlier.