Update from Gnulib

This incorporates:
2019-10-24 timespec-add, timespec-sub: simplify
* lib/timespec-add.c, lib/timespec-sub.c:
Copy from Gnulib.
1 job for master in 61 minutes and 31 seconds (queued for 5 seconds)
Status Job ID Name Coverage
  Test
failed #4125
test-all

01:01:31

 
Name Stage Failure
failed
test-all Test
Makefile:319: recipe for target 'check-doit' failed
make[2]: *** [check-doit] Error 1
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:294: recipe for target 'check-expensive' failed
make[1]: *** [check-expensive] Error 2
make[1]: Leaving directory '/builds/emacs/emacs/test'
Makefile:959: recipe for target 'check-expensive' failed
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1