Proper local system log semantics still need to be
created for Plan 9. In the meantime, the test suite
(viz., exp/gotype) expects there to be some Go
source for each import path. Thus, here is a stub,
equivalent to syslog_windows, for this purpose.

R=golang-dev, rsc, alex.brainman
CC=golang-dev
https://golang.org/cl/7000062