libfreeglut: add hash for license file

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libfreeglut/libfreeglut.hash

@@ -1,2 +1,5 @@
 # From http://sourceforge.net/projects/freeglut/files/freeglut/3.0.0/
 sha1	fca52242f9344627a30f11487ee42002e6b0dacd	freeglut-3.0.0.tar.gz
+
+# Hash for license file:
+sha256	b6593d5ec4c113a274abb85b10e8615895cb0ddb89f7912af5fe5aa8df38a275	COPYING