Fix old-style function definitions and enable warning. (#1651)

Function definitions with no parameters should always use the void keyword to allow the compiler to catch invalid calls of those functions at compile time.

Enable -Wold-style-definition to catch this early in the future.

Fixes #1649.

JerryScript-DCO-1.0-Signed-off-by: Tilmann Scheller t.scheller@samsung.com

targets/default/jerry-port-default-date.c

@@ -50,7 +50,7 @@ bool jerry_port_get_time_zone (jerry_time_zone_t *tz_p)
 /**
  * Default implementation of jerry_port_get_current_time.
  */
-double jerry_port_get_current_time ()
+double jerry_port_get_current_time (void)
 {
 #ifdef __GNUC__
   struct timeval tv;

targets/default/jerry-port-default-fatal.c

@@ -36,7 +36,7 @@ void jerry_port_default_set_abort_on_fail (bool flag) /**< new value of 'abort o
  * @return true - if 'abort on fail' flag is set,
  *         false - otherwise.
  */
-bool jerry_port_default_is_abort_on_fail ()
+bool jerry_port_default_is_abort_on_fail (void)
 {
   return abort_on_fail;
 } /* jerry_port_default_is_abort_on_fail */