Fix dns timeout for undefined syslog host

On some platforms, inet:getaddr can take several seconds to return when
passed the undefined atom, which is the default value of "syslog_host",
and therefore the value used when running tests. On platforms where it
takes longer to return than the test is allowed to run, the
couch_log_writer_syslog_test will fail with *timed out*.

This short circuits the case when "syslog_host" is undefined, and
removes the race from the test.

COUCHDB-3340
1 file changed
tree: f0c56d03dc9fcb538624d65c945f2508f8843895
  1. .gitignore
  2. .travis.yml
  3. LICENSE
  4. include/
  5. priv/
  6. rebar.config
  7. src/
  8. test/