Builds taking longer than a day to run

[Ade Lovett]

This is a long-outstanding bug in tinderbuild:

     echo "phase ${num} took $(env LANG=C date -u -j -r $((${end} - $ 
{start})) |
                 awk '{print $4}')"

if a build takes longer than a day, let's say, for the sake of  
argument, 32 hours, 2 minutes, 3 seconds, this will print:

     phase <x> took 08:02:03

a possible solution would be to add a new internal command as follows:

	tc epochTime [-s <start> -e <end>]

if both -s/-e are presented, then it'll kick back a string of the form:

	[<x> 'day'['s']] hh:mm:ss

if none are presented, it returns the time since the epoch (simple  
call to gmtime())

all other uses kick out an error.

Thoughts?

-aDe