idris: jailbreak to fix build with recent version of 'lens'

pkgs/development/compilers/idris/default.nix

···
   ];
   buildTools = [ happy ];
   extraLibraries = [ boehmgc gmp ];
-  configureFlags = "-fllvm -fgmp -fffi";
+  configureFlags = "-fgmp -fffi";
+  jailbreak = true;
   meta = {
     homepage = "http://www.idris-lang.org/";
     description = "Functional Programming Language with Dependent Types";