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.

headers/libs/glut/GL/glut.h

@@ -2,6 +2,8 @@
  * Copyright 1994-1997 Mark Kilgard, All rights reserved.
  * Distributed under the terms of the MIT License.
  *
+ * GPL licensing not permitted.
+ *
  * Authors:
  *      Mark Kilgard
  */

src/libs/glut/glut_bitmap.c

@@ -2,6 +2,8 @@
  * Copyright 1994-1997 Mark Kilgard, All rights reserved.
  * Distributed under the terms of the MIT License.
  *
+ * GPL licensing not permitted.
+ *
  * Authors:
  *	Mark Kilgard
  */

src/libs/glut/glut_bwidth.c

@@ -2,6 +2,8 @@
  * Copyright 1994-1997 Mark Kilgard, All rights reserved.
  * Distributed under the terms of the MIT License.
  *
+ * GPL licensing not permitted.
+ *
  * Authors:
  *      Mark Kilgard
  */

src/libs/glut/glut_ext.c

@@ -2,6 +2,8 @@
  * Copyright 1994-1997 Mark Kilgard, All rights reserved.
  * Distributed under the terms of the MIT License.
  *
+ * GPL licensing not permitted.
+ *
  * Authors:
  *      Mark Kilgard
  */

src/libs/glut/glut_shapes.c

@@ -2,6 +2,8 @@
  * Copyright 1994-1997 Mark Kilgard, All rights reserved.
  * Distributed under the terms of the MIT License.
  *
+ * GPL licensing not permitted.
+ *
  * Authors:
  *      Mark Kilgard
  */

src/libs/glut/glut_stroke.c

@@ -2,6 +2,8 @@
  * Copyright 1994-1997 Mark Kilgard, All rights reserved.
  * Distributed under the terms of the MIT License.
  *
+ * GPL licensing not permitted.
+ *
  * Authors:
  *      Mark Kilgard
  */

src/libs/glut/glut_swidth.c

@@ -2,6 +2,8 @@
  * Copyright 1994-1997 Mark Kilgard, All rights reserved.
  * Distributed under the terms of the MIT License.
  *
+ * GPL licensing not permitted.
+ *
  * Authors:
  *      Mark Kilgard
  */

src/libs/glut/glut_teapot.c

@@ -2,6 +2,8 @@
  * Copyright 1994-1997 Mark Kilgard, All rights reserved.
  * Distributed under the terms of the MIT License.
  *
+ * GPL licensing not permitted.
+ *
  * Authors:
  *      Mark Kilgard
  */

src/libs/glut/glut_util.c

@@ -2,6 +2,8 @@
  * Copyright 1994-1997 Mark Kilgard, All rights reserved.
  * Distributed under the terms of the MIT License.
  *
+ * GPL licensing not permitted.
+ *
  * Authors:
  *      Mark Kilgard
  */

src/libs/glut/glut_vidresize.c

@@ -2,6 +2,8 @@
  * Copyright 1994-1997 Mark Kilgard, All rights reserved.
  * Distributed under the terms of the MIT License.
  *
+ * GPL licensing not permitted.
+ *
  * Authors:
  *      Mark Kilgard
  */

src/libs/glut/glutbitmap.h

@@ -2,6 +2,8 @@
  * Copyright 1994-1997 Mark Kilgard, All rights reserved.
  * Distributed under the terms of the MIT License.
  *
+ * GPL licensing not permitted.
+ *
  * Authors:
  *      Mark Kilgard
  */

src/libs/glut/glutint.h

@@ -2,6 +2,8 @@
  * Copyright 1994-1997 Mark Kilgard, All rights reserved.
  * Distributed under the terms of the MIT License.
  *
+ * GPL licensing not permitted.
+ *
  * Authors:
  *      Mark Kilgard
  */

src/libs/glut/glutstroke.h

@@ -2,6 +2,8 @@
  * Copyright 1994-1997 Mark Kilgard, All rights reserved.
  * Distributed under the terms of the MIT License.
  *
+ * GPL licensing not permitted.
+ *
  * Authors:
  *      Mark Kilgard
  */