master updated (e4fb95f -> 4415534)

[Paul Eggert]

eggert pushed a change to branch master.

      from  e4fb95f   * lisp/emacs-lisp/bytecomp.el: Drop warning for loading 
into Emacs<23
      adds  818333c   * doc/lispref/os.texi (time-subtract): Doc fix.
      adds  363d927   Fix bug with JIT stealth timers
      adds  3cbf4cb   Eliminate use of cl-concatenate in 'seq' package
      adds  b16ba40   ; lisp/emacs-lisp/seq.el: Explain why we don't use cl-lib 
here
      adds  0a3682a   * src/timefns.c: Add comments.
       new  4415534   Merge from origin/emacs-27


Summary of changes:
 doc/lispref/os.texi         |  5 ++---
 lisp/emacs-lisp/cl-extra.el |  6 +-----
 lisp/emacs-lisp/seq.el      | 10 +++++++++-
 lisp/emacs-lisp/timer.el    |  2 +-
 src/timefns.c               | 32 ++++++++++++++++++++++++--------
 5 files changed, 37 insertions(+), 18 deletions(-)