bazel: Mark as broken on darwin

Fails with
```
0  0x103e67a51  __assert_rtn + 129
1  0x104040444  ld::passes::stubs::x86_64::classic::LazyPointerAtom::LazyPointerAtom(ld::passes::stubs::Pass&, ld::Atom const&, bool, bool) + 420
2  0x10403dc6a  ld::passes::stubs::Pass::makeStub(ld::Atom const&, bool) + 2762
3  0x10403ec5f  ld::passes::stubs::Pass::process(ld::Internal&) + 2511
4  0x10403f2c0  ld::passes::stubs::doPass(Options const&, ld::Internal&) + 128
5  0x103e68ff4  main + 1860
6  0x7fff68dc3cc9  start + 1
A linker snapshot was created at:
        /tmp/ijar-2020-11-01-111228.ld-snapshot
ld: Assertion failed: (targetAtom != NULL), function Fixup, file ../../../../ld64/src/ld/ld.hpp, line 776.
clang-6.0: error: linker command failed with exit code 1 (use -v to see invocation)
```

See NixOS#105573 for details.

pkgs/development/tools/build-managers/bazel/bazel_3/default.nix

@@ -164,6 +164,9 @@ stdenv.mkDerivation rec {
     description = "Build tool that builds code quickly and reliably";
     license = licenses.asl20;
     maintainers = [ maintainers.mboes ];
+    # fails on darwin with ld: Assertion failed: (targetAtom != NULL),
+    # remove once https://github.com/NixOS/nixpkgs/issues/105573 is resolved
+    broken = stdenv.isDarwin;
     inherit platforms;
   };