[logging] Flush after each message when logging to stderr

When logging to stderr, the relevance of timestamps can suffer from
unpredictable flush schedule if output happens to be block buffered.

Ensure stderr is flushed after each message.

Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

mce-log.c

@@ -2,8 +2,9 @@
  * @file mce-log.c
  * Logging functions for Mode Control Entity
  * <p>
- * Copyright © 2006-2007, 2010 Nokia Corporation and/or its subsidiary(-ies).
- * Copyright (C) 2012-2019 Jolla Ltd.
+ * Copyright (c) 2006 - 2007, 2010 Nokia Corporation and/or its subsidiary(-ies).
+ * Copyright (c) 2012 - 2020 Jolla Ltd.
+ * Copyright (c) 2020 Open Mobile Platform LLC.
  * <p>
  * @author David Weinehall <david.weinehall@nokia.com>
  * @author Simo Piiroinen <simo.piiroinen@jollamobile.com>
@@ -68,6 +69,7 @@ static void timestamp(struct timeval *tv)
 			mce_log_name(),
 			(long)diff.tv_sec, (long)(diff.tv_usec/1000),
 			"END OF BURST");
+		fflush(stderr);
 		start = *tv;
 	}
 	prev = *tv;
@@ -191,6 +193,7 @@ void mce_log_unconditional_va(loglevel_t loglevel, const char *const file,
 		(long)tv.tv_sec, (long)(tv.tv_usec/1000),
 		mce_log_level_tag(loglevel),
 		msg);
+	fflush(stderr);
     } else {
 	/* Use NOTICE priority when reporting LL_EXTRA
 	 * and LL_CRUCIAL logging */