Move syslog to //zircon/system/ulib

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

Change-Id: If82169a38920cca4edd5709cb9f8719ce0cd74ed
diff --git a/BUILD.gn b/BUILD.gn
index be2ae3c..62cb990 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -142,9 +142,9 @@
       "//sdk/fidl/fuchsia.hardware.goldfish",
       "//sdk/fidl/fuchsia.logger:fuchsia.logger_llcpp",
       "//sdk/fidl/fuchsia.sysmem",
-      "//zircon/public/lib/syslog-static",
       "//zircon/public/lib/zx",
       "//zircon/public/lib/zxio",
+      "//zircon/system/ulib/syslog:syslog-static",
       "//zircon/system/ulib/trace:trace-with-static-engine",
     ]