Add SyslogFacility option.

This patch adds the SyslogFacility option to torrc. This option allows
you to customize the logging facility passed to openlog(3). The default
value will continue to be the configure time constant LOGFACILITY.

See: https://bugs.torproject.org/25355
1 job for bugs/25355 in 30 minutes and 38 seconds
Status Job ID Name Coverage
  Test
failed #54275652
build

00:30:38

 
Name Stage Failure
failed
build Test
the 'fuzzing-corpora' repository.
SKIP src/test/fuzz_static_testcases.sh (exit status: 77)

SKIP: src/test/test_hs_ntor.sh
==============================

SKIP src/test/test_hs_ntor.sh (exit status: 77)

ERROR: Job failed: exit code 1