This change...
1. replaces calls to timet2fattime/fattime2timet with calls to
timespec2fattime/fattime2timespec. The functions got renamed shortly
after they landed in the kernel but the test code wasn't updated (see
7ea93e912bf0).
2. adds a utc_offset stub.
With this, the test code builds and runs as a 32-bit binary (cc -Wall -O2
-m32 subr_fattime.c).