Fix undefined references build errors on Windows (#3004)

We should emit function symbols for ecma_date_day, ecma_is_value_string and
ecma_number_is_nan inline functions, because they are used by unit tests:
unit-core/test-date-helpers.c, test-literal-storage.c and test-string-to-number.c.

JerryScript-DCO-1.0-Signed-off-by: Csaba Osztrogonác oszi@inf.u-szeged.hu

jerry-core/ecma/base/ecma-helpers-number.c

@@ -240,7 +240,7 @@ ecma_number_get_sign_field (ecma_number_t num) /**< ecma-number */
                   fraction is filled with anything but not all zero bits,
  *         false - otherwise
  */
-inline bool JERRY_ATTR_ALWAYS_INLINE
+extern inline bool JERRY_ATTR_ALWAYS_INLINE
 ecma_number_is_nan (ecma_number_t num) /**< ecma-number */
 {
   bool is_nan = (num != num);