* src/timefns.c (syms_of_timefns) <current-time-list>:
* etc/NEWS:
* doc/lispref/os.texi (Time of Day): Fix a typo.

Change current-time and related functions back to using the
traditional list form.  Also, add a new boolean variable
current-time-list that lets people try out (TICKS . HZ) form,
with the goal of smoothing the transition.
* src/timefns.c (CURRENT_TIME_LIST): Change default back to true.
(current-time-list): New boolean Lisp variable, which defaults to
CURRENT_TIME_LIST.  All uses of CURRENT_TIME_LIST changed to
use current_time_list, and all documentation changed.

* doc/lispref/os.texi (Time of Day): Document it.
* src/timefns.c (Fcurrent_cpu_time): New function (bug#44674).

* src/timefns.c (CURRENT_TIME_LIST): Change default to false.
All documentation changed.

* src/timefns.c (Fencode_time): Add support for a 6-elt list arg.
Requested by Max Nikulin for Org (bug#54764).
* test/src/timefns-tests.el (encode-time-alternate-apis): New test.

* doc/lispref/os.texi (Time of Day, Time Conversion):
Move the warnings about DST being -1 to closer to where DST is
discussed, and reword and improve the discussions and warnings.
Be more precise about years before 1969 (possible west of UTC) vs the
Epoch.  Mention some problems due to leap seconds, leap years,
daylight saving transitions, and time zone changes.  Modernize
discussion of OS timestamp range.  Prefer secular ‘BCE’ to religious
‘BC’.  Omit discussion of decoded-time-add and make-decoded-time, as
they are in a library and are not always available; instead, mention
the library.  Warn about common mistakes when doing simple date
arithmetic.
* src/timefns.c (Fencode_time): In doc string, mention date
arithmetic and tighten up the wording a bit.

* doc/lispref/os.texi (Time Conversion): Add a warning that blind
changing of code calling `encode-time' to use single list instead of
multiple values may cause deferred bugs since it is common to use nil
for ignored arguments such as DST in the old calling convention.
* src/timefns.c (encode-time): Mention the warning added to the elisp
reference in the docstring.

Refactoring related to `encode-time' caused (bug#54731), so it is better
to make apparent the difference between the recommended and the
obsolescent ways to call the function.  More details concerning the
purpose and limitations of the DST field are added after discussion with
Paul Eggert in (bug#54764).

* test/src/timefns-tests.el (time-equal-p-NaN-NaN): New test.

* timefns.c (time_cmp): Defer the calculation of the time struct, in
  case A and B are eq to one another.

* src/comp.c (saved_sigset, helper_temp_output_buffer_setup):
Remove; unused.
* src/comp.c (logfile, helper_link_table):
* src/fns.c (hashfn_equal, hashfn_eql):
* src/frame.c (frame_windows_min_size):
* src/gnutls.c (emacs_gnutls_global_init):
* src/minibuf.c (Vcommand_loop_level_list):
* src/syntax.c (syntax_code_spec):
* src/timefns.c (time_overflow):
* src/xterm.c (x_xrender_color_from_gc_foreground)
(x_display_set_last_user_time):
Now static, since it’s not used elsewhere.
* src/xterm.c (x_xrender_color_from_gc_foreground)
(x_xrender_color_from_gc_background): Move earlier to avoid
forward use.
(x_xrender_color_from_gc_foreground): Do not define unless
!defined USE_CAIRO && (RENDER_MAJOR > 0 || RENDER_MINOR >= 2),
since it’s not used otherwise.