There were ultimately two separate problems here:
- a 32-bit long cannot represent microseconds since 1970 (noted by ian)
- time_t is 32-bit on i386, so now() was wrong anyways even with the correct
return type.
For the first, just explicitly use a uint64_t for now() and all of the
callers. For the second, we need to explicitly cast tv_sec to uint64_t
before it gets multiplied in the SEC_TO_US macro. Casting this instance
rather than generally in the macro was arbitrarily chosen simply because all
other uses are converting small relative time values.
The tests now pass on i386, at least; presumably other ILP32 will be fine
now as well.