cross compiled macos binaries with LLD which depend on TLS fail at runtime

```zig
threadlocal var x: i32 = 1;
test "tls macos cross compile" {
    x += 1;
}
```

```
$ ./zig test test.zig
(ok)
$ ./zig test test.zig -target x86_64-macosx
dyld: Symbol not found: __tlv_bootstrap
```