Run admin/update-copyright.

(timerfd_callback): Ignore weird events with no data.  Add tight
assertions and comments.
(init_atimer) [HAVE_TIMERFD]: Add environment variable to optionally
disabletimerfd-based timer.  Use TFD_NONBLOCK for timer descriptor.

* configure.ac (HAVE_TIMERFD): Define only if TFD_CLOEXEC works,
since the code leaked file descriptors to children when !TFD_CLOEXEC.
(HAVE_TIMERFD_CLOEXEC): Remove; no longer used.
* m4/clock_time.m4 (gl_CLOCK_TIME): Don't check for clock_getres.
This reverts the previous change to this file, so it matches
gnulib again.
* src/atimer.c (TIMERFD_CREATE_FLAGS): Remove; we now assume TFD_CLOEXEC.
(alarm_timer, alarm_timer_ok, set_alarm, init_atimer):
Fall back on timer_create if timerfd_create fails at runtime.
(resolution) [HAVE_CLOCK_GETRES]: Remove; we now rely on the
kernel primitives to do resolution.  All uses removed.
(timerfd) [!HAVE_TIMERFD]: Define to be -1, for convenience.
(turn_on_atimers): Clear timer_create-based timers too,
for consistency.

<http://lists.gnu.org/archive/html/emacs-devel/2014-07/msg00370.html>.
* atimer.c (timerfd_callback): Always read expiration data.
Add comment.
(turn_on_atimers) [HAVE_TIMERFD]: Disarm timerfd timer.
* process.c (add_timer_wait_descriptor): Add timer descriptor
to input_wait_mask and non_process_wait_mask as well.

* configure.ac (toplevel): Check whether GNU/Linux-specific
timerfd functions and macros are available.
* m4/clock_time.m4 (gl_CLOCK_TIME): Check for clock_getres as well.
* src/atimer.c (toplevel) [HAVE_TIMERFD]: Include sys/timerfd.h.
(toplevel): Rename alarm_timer_ok to special_timer_available.
[HAVE_TIMERFD]: Declare timerfd.
[HAVE_CLOCK_GETRES]: Declare resolution.
(start_atimer) [HAVE_CLOCK_GETRES]: Round up timestamp to
system timer resolution.
(set_alarm) [HAVE_TIMERFD]: Use timerfd_settime.
(timerfd_callback) [HAVE_TIMERFD]: New function.
(atimer_result, debug_timer_callback, Fdebug_timer_check)
[ENABLE_CHECKING]: New function for the sake of automated tests.
(init_atimer) [HAVE_TIMERFD]: Setup timerfd.
[HAVE_CLOCK_GETRES]: Likewise for system timer resolution.
[ENABLE_CHECKING]: Defsubr test function.
* src/atimer.h (timerfd_callback) [HAVE_TIMERFD]: Add prototype.
* src/lisp.h (add_timer_wait_descriptor) [HAVE_TIMERFD]: Likewise.
* src/process.c (add_timer_wait_descriptor) [HAVE_TIMERFD]: New function.
* test/automated/timer-tests.el (timer-tests-debug-timer-check): New test.

because atimer expiration is absolute rather than relative.

* atimer.c (block_atimers):
* callproc.c (block_child_signal): Block SIGINT too;
otherwise, its handler might now unblock signals that it shouldn't.
* keyboard.c (read_char): Clear signal mask, since we may
be in a SIGINT handler, and many signals may be masked.
* keyboard.c (handle_interrupt):
* sysdep.c (handle_arith_signal):
Clear signal mask instead of just unblocking the signal that
was received, since several signals may be blocked at this point.

Fixes: debbugs:17561

* atimer.c (sigmask_atimers): Remove.
Remaining use rewritten to use body of this function.
* atimer.c (block_atimers, unblock_atimers):
* callproc.c (block_child_signal, unblock_child_signal):
* sysdep.c (block_tty_out_signal, unblock_tty_out_signal):
New arg OLDSET.  All callers changed.
* atimer.c (block_atimers, unblock_atimers):
* callproc.c (block_child_signal, unblock_child_signal):
* keyboard.c (handle_interrupt):
* sound.c (vox_configure, vox_close):
Restore the old signal mask rather than unilaterally clearing bits
from the mask, in case a handler is running within another
handler.  All callers changed.
* lisp.h, process.c, process.h, term.c:
Adjust decls and callers to match new API.
* sysdep.c (emacs_sigaction_init): Don't worry about masking SIGFPE;
signal handlers aren't supposed to use floating point anyway.
(handle_arith_signal): Unblock just SIGFPE rather than clearing mask.

Fixes: debbugs:15561

This portability layer is no longer needed, since Emacs has been
using struct timespec as a portability layer for some time.
Merge from gnulib, incorporating:
2013-08-27 timespec: new convenience constants and function
* src/atimer.h, src/buffer.h, src/dispextern.h, src/xgselect.h:
Include <time.h> rather than "systime.h"; that's all that's needed now.
* src/dispnew.c: Include <timespec.h> rather than "systime.h";
that's all that's needed now.
* src/systime.h (EMACS_TIME): Remove.  All uses changed to struct timespec.
(EMACS_TIME_RESOLUTION): Remove.  All uses changed to
TIMESPEC_RESOLUTION.
(LOG10_EMACS_TIME_RESOLUTION): Remove.  All uses changed to
LOG10_TIMESPEC_RESOLUTION.
(EMACS_SECS, emacs_secs_addr): Remove.  All uses changed to tv_sec.
(EMACS_NSECS): Remove.  All uses changed to tv_nsec.
(make_emacs_time): Remove.  All used changed to make_timespec.
(invalid_timespec): Rename from invalid_emacs_time.  All uses changed.
(current_timespec): Rename from current_emacs_time.  All uses changed.
(add_emacs_time): Remove.  All uses changed to timespec_add.
(sub_emacs_time): Remove.  All uses change dot timespec_sub.
(EMACS_TIME_SIGN): Remove.  All uses changed to timespec_sign.
(timespec_valid_p): Rename from EMACS_TIME_VALID_P.  All uses changed.
(EMACS_TIME_FROM_DOUBLE): Remove.  All uses changed to dtotimespec.
(EMACS_TIME_TO_DOUBLE): Remove.  All uses changed to timespectod.
(current_timespec): Rename from current_emacs_time.  All uses changed.
(EMACS_TIME_EQ, EMACS_TIME_LT, EMACS_TIME_LE): Remove.  All uses
changed to timespec_cmp.
* src/xgselect.c: Include <timespec.h>, since our .h files don't.