lldb-3.5 is broken, bug in the cmake

lldb-3.6 is working (just waiting on a staging fix to merge), so let's just
mark this broken until we decide to nuke 3.5 all together.

Fixes #6636 refs #6668

pkgs/development/compilers/llvm/3.5/lldb.nix

@@ -40,5 +40,6 @@ stdenv.mkDerivation {
     license     = stdenv.lib.licenses.bsd3;
     maintainers = [ stdenv.lib.maintainers.shlevy ];
     platforms   = stdenv.lib.platforms.all;
+    broken = true;
   };
 }