Automatic merge from submit-queue (batch tested with PRs 51047, 48573, 50764, 51092, 50578)

Use `select` to disable building static binaries if `--cpu=darwin`.

This change allows kubectl to be built on MacOS machines using
`bazel build //cmd/kubectl`.
    
Mac OS X doesn't support static binaries because it does not have a
stable syscall API. Userspace binaries are expected to dynamically
link against libcrt instead.
    
https://developer.apple.com/library/content/qa/qa1118/_index.html

```release-note
None
```