Make sntpSync use setTime() not to break setInterval()
Make sntpSync use setTime() not to break setInterval()

The setTime() properly sets the jsiLastIdleTime which is used
in the _jswrap_interface_setTimeoutOrInterval to trigger timers.

Update the time only when the mDNS returns non-null value.

wilberforce/Espruino,lancernet/Espruino,lancernet/Espruino,wilberforce/Espruino,lancernet/Espruino,lancernet/Espruino,luetgendorf/Espruino,luetgendorf/Espruino,luetgendorf/Espruino,wilberforce/Espruino,lancernet/Espruino,lancernet/Espruino,luetgendorf/Espruino,luetgendorf/Espruino,lancernet/Espruino,luetgendorf/Espruino,wilberforce/Espruino,wilberforce/Espruino,wilberforce/Espruino,wilberforce/Espruino,luetgendorf/Espruino