Introduce the Date Port API

Replaced `gettimeofday`-related code with `jerry_port_get_current_time`
and `jerry_port_get_time_zone` function calls. Moved old code to
default port implementation.

Removed `ENABLE_DATE_SYS_CALLS` as date syscalls should "just work".

Fix DST adjustments: even if `gettimeofday` returns meaningful data in
`tz_dsttime`, the value is just a flag (or, according to some sources,
a tri-state value: >0 if DST applies, ==0 if DST does not apply, <0 if
unknown). Hitherto, the field was simply added to/subtracted from a
time value in milliseconds. To use it approximately correctly, the
field's value should be multiplied by "millisecs/hour".

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

jerry-core/CMakeLists.txt

@@ -192,11 +192,6 @@ project (JerryCore C ASM)
    set(DEFINES_JERRY ${DEFINES_JERRY} JERRY_ENABLE_LOG)
   endif()
 
- # Date system calls
-  if("${ENABLE_DATE_SYS_CALLS}" STREQUAL "ON")
-   set(DEFINES_JERRY ${DEFINES_JERRY} JERRY_ENABLE_DATE_SYS_CALLS)
-  endif()
-
  # Fill error messages for builtin error objects
   if("${ENABLE_ERROR_MESSAGES}" STREQUAL "ON")
    set(DEFINES_JERRY ${DEFINES_JERRY} JERRY_ENABLE_ERROR_MESSAGES)