xwayland: Silence X wm debug logging

Much to verbose for default logging.  Use a wm_log() wrapper that we can
toggle on/off as needed.  Maybe we're ready for log domains now.
diff --git a/src/log.c b/src/log.c
index 1c05e25..834bbd6 100644
--- a/src/log.c
+++ b/src/log.c
@@ -93,24 +93,44 @@
 }
 
 WL_EXPORT int
+weston_vlog(const char *fmt, va_list ap)
+{
+	int l;
+
+	l = weston_log_timestamp();
+	l += vfprintf(weston_logfile, fmt, ap);
+
+	return l;
+}
+
+WL_EXPORT int
 weston_log(const char *fmt, ...)
 {
 	int l;
 	va_list argp;
+
 	va_start(argp, fmt);
-	l = weston_log_timestamp();
-	l += vfprintf(weston_logfile, fmt, argp);
+	l = weston_vlog(fmt, argp);
 	va_end(argp);
+
 	return l;
 }
 
 WL_EXPORT int
+weston_vlog_continue(const char *fmt, va_list argp)
+{
+	return vfprintf(weston_logfile, fmt, argp);
+}
+
+WL_EXPORT int
 weston_log_continue(const char *fmt, ...)
 {
 	int l;
 	va_list argp;
+
 	va_start(argp, fmt);
-	l = vfprintf(weston_logfile, fmt, argp);
+	l = weston_vlog_continue(fmt, argp);
 	va_end(argp);
+
 	return l;
 }