libwebsockets

lws_compare_time_t: conceal time discontiguities on all platforms

This provides platform-independent support for time discontiguities.

On embedded without battery RTC, commonly we only get time after
NTP completes.  This makes the cert checking happen when we have
a reasonable time and introduces lws_compare_time_t() to correctly
compare time_t s that may sit on either side of a time discontiguity.