ref: f6bff3c0830c1fe63dc45cd84d0a0a3a67b0cdf0 dir: /sys/src/ape/lib/ap/gen/difftime.c/
#include <time.h> /* Difference in seconds between two calendar times */ double difftime(time_t t1, time_t t0) { return (double)t1-(double)t0; }