cluster: remove duplicate this.errno assignment
cluster: fix shared handle bind error propagation

A failed bind() was already being correctly reported in round-robin
mode. This commit fixes bind() error reporting in shared handle mode.

Fixes #5774.
test: cluster: add 'bind to privileged port' tests
src: remove unused tick_spinner
test: loosen timeout in https-no-reader

fix #5925
child_process: add 'shell' option to .exec()

No test, we can't rely on an alternate shell being available.

Fixes #5935.
doc: vm: fix incorrect API documentation

On timeout, an Error object is thrown, not null.