cpp/chrono/file clock/to from sys

@1@ Converts the  to a  representing the same point in time. @2@ Converts the  to a  representing the same point in time.

The duration of the return type is computed from in an unspecified manner.

These function templates are optional: an implementation may choose to instead provide and.

Return value
@1@ A representing the same point in time as the argument. @2@ A representing the same point in time as the argument.