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

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

@@ -0,0 +1,55 @@
+/* Copyright 2014-2016 Samsung Electronics Co., Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdarg.h>
+
+#include "jerry-port.h"
+
+/**
+ * Provide log message to filestream implementation for the engine.
+ */
+int jerry_port_logmsg (FILE *stream, /**< stream pointer */
+                       const char *format, /**< format string */
+                       ...) /**< parameters */
+{
+  va_list args;
+  int count;
+  va_start (args, format);
+  count = vfprintf (stream, format, args);
+  va_end (args);
+  return count;
+} /* jerry_port_logmsg */
+
+/**
+ * Provide error message to console implementation for the engine.
+ */
+int jerry_port_errormsg (const char *format, /**< format string */
+                         ...) /**< parameters */
+{
+  va_list args;
+  int count;
+  va_start (args, format);
+  count = vfprintf (stderr, format, args);
+  va_end (args);
+  return count;
+} /* jerry_port_errormsg */
+
+/**
+ * Provide output character to console implementation for the engine.
+ */
+int jerry_port_putchar (int c) /**< character to put */
+{
+  return putchar ((unsigned char) c);
+} /* jerry_port_putchar */