MT#55283 Prevent warning logs when recording-method is pcap

If recording-method is pcap, then proc is zero-initialized, so
meta_filepath is empty. This shows many logs such as:

[core] Failed to open recording metadata file '(null)' for writing: Bad address

Prevent them by returning earlier.

Closes #1889

Change-Id: Ifeb3038f9a5c0bd6a9b7dd92842dd61783b40263

daemon/recording.c

@@ -847,6 +847,8 @@ static int append_meta_chunk(struct recording *recording, const char *buf, unsig
 		const char *label_fmt, ...)
 {
 	va_list ap;
+	if (!recording->proc.meta_filepath)
+		return -1;
 	va_start(ap, label_fmt);
 	int ret = vappend_meta_chunk(recording, buf, buflen, label_fmt, ap);
 	va_end(ap);