Issue a message on `C-x o' and there's no other window

* lisp/window.el (other-window): Issue a message when the user
types `C-x o' and there's no other window to select (bug#10999).
1 job for master in 90 minutes and 3 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Test
failed #3022
test-all

01:30:03

 
Name Stage Failure
failed
test-all Test The script exceeded the maximum execution time set for the job
  GEN      lisp/international/ccl-tests.log
ELC lisp/international/mule-tests.elc
GEN lisp/international/mule-tests.log
ELC lisp/international/mule-util-tests.elc
GEN lisp/international/mule-util-tests.log
ELC lisp/international/ucs-normalize-tests.elc
GEN lisp/international/ucs-normalize-tests.log
Pulling docker image gitlab/gitlab-runner-helper:x86_64-d0b76032 ...
ERROR: Job failed: execution took longer than 1h30m0s seconds