leaps: mark as broken

The package sha256 is wrong. After fixing it the build has dependency
issues like:

    go/src/github.com/jeffail/leaps/cmd/leaps/bindata_assetfs.go:203:2:
    cannot find package "github.com/elazarl/go-bindata-assetfs" in any
    of:

/cc @qknight

pkgs/development/tools/leaps/default.nix

@@ -21,5 +21,6 @@ buildGoPackage rec {
     license = "MIT";
     maintainers = with stdenv.lib.maintainers; [ qknight ];
     meta.platforms = stdenv.lib.platforms.linux;
+    broken = true;
   };
 }