Move syslog to //zircon/system/ulib

This fixes build after https://fuchsia-review.googlesource.com/c/fuchsia/+/388456
landed.

Bug: 154346346
Test: presubmit
Merged-In: If82169a38920cca4edd5709cb9f8719ce0cd74ed
Change-Id: I8c249c69d076738ae2c03027568af12285c6fa9a
1 file changed