targets: zephyr: Reinstate "print" function and error printing. (#1851)

Re-add "print" function following resent refactors when it was moved
from jerry-core to jerry-ext. This is done in particular to keep
detailed messages on errors.

JerryScript-DCO-1.0-Signed-off-by: Paul Sokolovsky paul.sokolovsky@linaro.org

targets/zephyr/src/jerry-port.c

@@ -72,3 +72,13 @@ jerry_port_get_time_zone (jerry_time_zone_t *tz_p)
 
   return true;
 } /* jerry_port_get_time_zone */
+
+/**
+ * Provide the implementation of jerryx_port_handler_print_char.
+ * Uses 'printf' to print a single character to standard output.
+ */
+void
+jerryx_port_handler_print_char (char c) /**< the character to print */
+{
+  printf ("%c", c);
+} /* jerryx_port_handler_print_char */