Introduce the Termination Port API

* Moved the error codes to jerry-port.h and declared port function
  `jerry_port_fatal`.

* Moved "exit or abort on fail" functionality to the newly added
  jerry-port-default-fatal.c.

* This implied that a default port-specific API had to be introduced:
  functions `jerry_port_default_set_abort_on_fail` and
  `jerry_port_default_is_abort_on_fail` declared in jerry-port-default.h
  control the fatal exit behaviour.

* For the sake of clarity, renamed jerry-port.c to
  jerry-port-default-io.c.

* Adapted CMakeLists to deal with port implementations consisting of
  more then one source file and exposing headers. This also required
  the renaming of `EXTERNAL_PORT_FILE` cmake option to
  `EXTERNAL_PORT_DIR`.

* Adapted main sources to use the default port header for the
  abort-on-fail functionality, as that is not part of the core jerry
  API anymore.

* Added default port implementation to the static source code checker
  tools.

JerryScript-DCO-1.0-Signed-off-by: Akos Kiss akiss@inf.u-szeged.hu

jerry-core/jerry.c

@@ -1689,18 +1689,6 @@ jerry_get_memory_limits (size_t *out_data_bss_brk_limit_p, /**< [out] Jerry's ma
   *out_stack_limit_p = CONFIG_MEM_STACK_LIMIT;
 } /* jerry_get_memory_limits */
 
-/**
- * Check whether 'abort' should be called instead of 'exit' upon exiting with non-zero exit code.
- *
- * @return true - if 'abort on fail' flag is set,
- *         false - otherwise.
- */
-bool
-jerry_is_abort_on_fail (void)
-{
-  return ((jerry_flags & JERRY_FLAG_ABORT_ON_FAIL) != 0);
-} /* jerry_is_abort_on_fail */
-
 /**
  * Parse script for specified context
  *