Commit Briefs
Add missing includes for time() and ctime()
These headers were implicitly used on OpenBSD, but building on Linux revealed that <time.h> wasn't included directly. diffreg.c uses ctime(), which additionally needs <sys/types.h>.
Remove return value from diffreg's fetch()
The last use of this was removed in 0165cdf03ffac4c24334979832ad27554913d54c over a year ago.
got_error_from_errno -> got_error_prefix_errno
also add got_error_prefix_errno2 and got_error_prefix_errno3 which should hopefully all be merged into a single function with variadic args (but can't alloc mem)