Fixes the following:
* Read past buffer end in intToDatetime / intToTime
* Allow intToTime to convert datetime
* Allow intToTime to convert shortened time values
* Allow stringToTime to convert datetime and int time values
* Fix saturation / bad values in intToTime and stringToTime
* Fix TIME return in STR_TO_DATE()
* Fix NULL return on type inequality for TIMEDIFF()
* Fix zero day calculation error in ADDTIME()/SUBTIME()
* Fix DATETIME to int calculation error in aggregate bit operations
* Make the new harderning flags optional with -DSECURITY_HARDENED_NEW