* lib/mktime.c: Include stdbool.h, intprops.h, verify.h.
(WRAPV): Remove; no longer needed.
(verify): Remove. Replace all uses with call to verify.h 'verify'.
(TYPE_IS_INTEGER, TYPE_SIGNED, TYPE_MINIMUM, TYPE_MAXIMUM):
Remove. Use intprops.h defns instead.
(leapyear, isdst_differ, time_t_add_ok, time_t_int_ok):
Use bool for Boolean, for clarity.
(time_t_add_ok, time_t_int_add_ok): Use INT_ADD_WRAPV to
detect integer overflow.
* modules/mktime (Depends-on): Add intprops, stdbool, verify.