unix: re-allow WRONLY fd in uv_read_start

[fantix]

For the writing end (O_WRONLY) of a pipe(2), we should also allow polling for read, so that the user could listen for a broken pipe on the writing end using uv_read_start() without having to try to write anything to the pipe, or wait until the next write to find out.

Fixes: https://github.com/libuv/libuv/issues/2058

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[fantix]

@santigimeno a gentle reminder that the requested changes are committed, thanks for re-checking!

[santigimeno]

CI: https://ci.nodejs.org/view/libuv/job/libuv-test-commit/2120/

[fantix]

@santigimeno Thank you! I believe now the failing tests are fixed.