Make wimlib on 32-bit Windows year 2038 safe by doing the following:
- Build both the library and program with 64-bit time_t, being careful
to avoid changing the timespec struct exposed in the API.
- Update wimlib's API to include an extended seconds field in
wimlib_dir_entry for each timestamp, and set it when tv_sec is 32-bit.
- When needing the current time, call GetSystemTimeAsFileTime() instead
of MinGW's gettimeofday().
This also has the advantage that due to switching to the 64-bit time_t
functions, 32-bit wimlib-imagex.exe now prints timestamps prior to year
1970 correctly.
Unfortunately, despite the API improvement, we cannot at this time make
wimlib fully Y2038-safe on 32-bit UNIX, due to lack of OS support.