Bug #55755 : Date STD variable signness breaks server on FreeBSD and OpenBSD

* Added a check to configure on the size of time_t
* Created a macro to check for a valid time_t that is safe to use with datetime 
  functions and store in TIMESTAMP columns.
* Used the macro consistently instead of the ad-hoc checks introduced by 52315
* Fixed compliation warnings on platforms where the size of time_t is smaller than
  the size of a long (e.g. OpenBSD 4.8 64 amd64).

Bug #52315: utc_date() crashes when system time > year 2037

* Added a correct check for the timestamp range instead of just variable size check to
SET TIMESTAMP.
* Added overflow checking before converting to time_t. 
* Using a correct localized error message in this case instead of the generic error.
* Added a test suite.
* fixed the checks so that they check for unsigned time_t as well. Used the checks 
  consistently across the source code.
* fixed the original test case to expect the new error code.