hooks: take advantage of strftime's %N format

hooks: take advantage of strftime's %N format

By using our own strftime utility instead of the date utility we
can take advantage of the %N format (nanoseconds) and even though
it only has microsecond granularity, that's far superior to the
single second granularity of the date command.

Additionally it provides the "extra semantics" of doing a usleep(1)
both before and after the call to gettimeofday when using the %N
specifier.

Replace the two "sleep 1" calls and the single "date" call with a
"strftime" call using %N and adjust the surrounding code to massage
that output into a unique name using microseconds while still
providing the HHMMSS value needed for writing into the log.

This does require that strftime be installed into the chroot jail now.

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>