This patch merges the upstream NetBSD syslog.[ch], which adds syslogp()
family of APIs to support RFC5424. This API will first go into use in
the logger tool, klogd, and syslog_tst, then it will also be exposed
as libsyslog and syslog/syslog.h for end-users.
Signed-off-by: Joachim Nilsson <troglobit@gmail.com>