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

tools/check-vera.sh

@@ -16,6 +16,7 @@
 # limitations under the License.
 
 JERRY_CORE_FILES=`find ./jerry-core -name "*.c" -or -name "*.h"`
+JERRY_PORT_DEFAULT_FILES=`find ./targets/default -name "*.c" -or -name "*.h"`
 JERRY_LIBC_FILES=`find ./jerry-libc -name "*.c" -or -name "*.h"`
 JERRY_LIBM_FILES=`find ./jerry-libm -name "*.c" -or -name "*.h"`
 JERRY_MAIN_FILES=`find . -maxdepth 1 -name "*.c" -or -name "*.h"`
@@ -23,4 +24,4 @@ UNIT_TEST_FILES=`find ./tests/unit -name "*.c" -or -name "*.h"`
 
 vera++ -r tools/vera++ -p jerry \
  -e --no-duplicate \
- $JERRY_CORE_FILES $JERRY_LIBC_FILES $JERRY_LIBM_FILES $JERRY_MAIN_FILES $UNIT_TEST_FILES
+ $JERRY_CORE_FILES $JERRY_PORT_DEFAULT_FILES $JERRY_LIBC_FILES $JERRY_LIBM_FILES $JERRY_MAIN_FILES $UNIT_TEST_FILES