Cannot compile RTC.ino example about m5unified

[lovyan03]

@patfelst
Thanks for reporting this Issue.
It seems that there was a missing header file that should be included.
Please try adding the following code to the top of the sample code.

#include <esp_sntp.h>

[patfelst]

Yes thanks, that fixed the problem! And it works reliably now, good NTP sync every time!

In case anyone else is reading this, for my home location in Adelaide, Australia, this is the function call that's working for me:
configTzTime("ACST-9:30ACDT,M10.1.0,M4.1.0/3", "pool.ntp.org");