Turn more licenses into lib.licenses style

Should eval cleanly, as far as -A tarball tells me.

Relevant: issue #2999, issue #739

pkgs/development/libraries/mesa-glu/default.nix

@@ -14,6 +14,6 @@ stdenv.mkDerivation rec {
   meta = {
     description = "OpenGL utility library";
     homepage = http://cgit.freedesktop.org/mesa/glu/;
-    license = "bsd"; # SGI-B-2.0, which seems BSD-like
+    license = stdenv.lib.licenses.sgi-b-20;
   };
 }