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

jerry-core/jmem/jmem-allocator.c

@@ -37,7 +37,7 @@ jmem_init (void)
  * Finalize memory allocators.
  */
 void
-jmem_finalize ()
+jmem_finalize (void)
 {
   jmem_pools_finalize ();