[O] org-agenda.el acquired a dependency on org-clock.el

[Nick Dokos]

Commit 8c3ecbe3 introduced a new dependency

 org-agenda.el --> org-clock.el

by moving the org-hh:mm-string-to-minutes etc. functions into org-clock.el.
Presumably, org-agenda.el now needs a

 (require 'org-clock)

Nick