Merge changes made in Emacs trunk.

Merge changes made in Emacs trunk.

smime.el (from): Remove unused declaration.
gnus-util.el (with-no-warnings): Remove compat stub, now unused.
gnus-util.el (gnus-float-time): On Emacs, always an alias.
ecomplete.el (with-no-warnings): Remove compat stub, now unused.
ecomplete.el (ecomplete-add-item): Use float-time on Emacs, else gnus-float-time.
time-date.el (time-to-seconds): Always an alias on Emacs, never a real function.
time-date.el (with-no-warnings): Remove compat stub, now unused.
time-date.el (time-less-p): Doc fix.
time-date.el (time-to-number-of-days): Simplify.