make struct initialization C99 compatible again

Mainly change {} to { 0 } to remove a pedantic warning.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

testj1939.c

@@ -61,7 +61,7 @@ static void onsigalrm(int sig)
 
 static void schedule_oneshot_itimer(double delay)
 {
-	struct itimerval it = {};
+	struct itimerval it = { 0 };
 
 	it.it_value.tv_sec = delay;
 	it.it_value.tv_usec = (long)(delay * 1e6) % 1000000;