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

docs/05.PORT-API.md

@@ -196,7 +196,7 @@ 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)
 {
   struct timeval tv;