cmake: add bsd3 license

pkgs/development/tools/build-managers/cmake/2.8.nix

···
     description = "Cross-Platform Makefile Generator";
     platforms = if useQt4 then qt4.meta.platforms else stdenv.lib.platforms.unix;
     maintainers = with stdenv.lib.maintainers; [ ];
+    license = stdenv.lib.licenses.bsd3;
   };
 }

pkgs/development/tools/build-managers/cmake/default.nix

···
     description = "Cross-Platform Makefile Generator";
     platforms = if useQt4 then qt4.meta.platforms else platforms.all;
     maintainers = with maintainers; [ ttuegel lnl7 ];
+    license = licenses.bsd3;
   };
 }