Syslog: added "nohostname" option.

The option disables sending hostname in the syslog message header.  This is
useful with syslog daemons that do not expect it (tickets #677 and #783).

src/core/ngx_syslog.c

diff --git a/src/core/ngx_syslog.c b/src/core/ngx_syslog.c
index d4e79f6..08f4c04 100644
--- a/src/core/ngx_syslog.c
+++ b/src/core/ngx_syslog.c
@@ -194,6 +194,9 @@
             peer->tag.data = p + 4;
             peer->tag.len = len - 4;
 
+        } else if (len == 10 && ngx_strncmp(p, "nohostname", 10) == 0) {
+            peer->nohostname = 1;
+
         } else {
             ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                "unknown syslog parameter \"%s\"", p);
@@ -220,6 +223,11 @@
 
     pri = peer->facility * 8 + peer->severity;
 
+    if (peer->nohostname) {
+        return ngx_sprintf(buf, "<%ui>%V %V: ", pri, &ngx_cached_syslog_time,
+                           &peer->tag);
+    }
+
     return ngx_sprintf(buf, "<%ui>%V %V %V: ", pri, &ngx_cached_syslog_time,
                        &ngx_cycle->hostname, &peer->tag);
 }

src/core/ngx_syslog.h

diff --git a/src/core/ngx_syslog.h b/src/core/ngx_syslog.h
index a915051..cc4c842 100644
--- a/src/core/ngx_syslog.h
+++ b/src/core/ngx_syslog.h
@@ -16,7 +16,8 @@
 
     ngx_addr_t        server;
     ngx_connection_t  conn;
-    ngx_uint_t        busy;  /* unsigned busy:1; */
+    unsigned          busy:1;
+    unsigned          nohostname:1;
 } ngx_syslog_peer_t;