emacsclient: omit EXTRA_SPACE guesswork

* lib-src/emacsclient.c: Include <intprops.h>.
(EXTRA_SPACE): Remove; code no longer guesses this is enough.
(open_config): New function.
(get_server_config): Use it.
(set_local_socket): Compute upper bound of buffer size
instead of guessing via EXTRA_SPACE.
1 job for master in 21 minutes and 30 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
failed #118
test

00:21:30

 
Name Stage Failure
failed
test Test
Makefile:301: recipe for target 'check-doit' failed
make[2]: *** [check-doit] Error 1
make[2]: Leaving directory '/builds/tzz/emacs/test'
Makefile:271: recipe for target 'check' failed
make[1]: *** [check] Error 2
make[1]: Leaving directory '/builds/tzz/emacs/test'
make: *** [check] Error 2
Makefile:955: recipe for target 'check' failed
ERROR: Job failed: exit code 1