[ccache] PATCH: Add cwd/hostname to logfiles

[Wilson Snyder]

I'm debugging a problem which will be the topic of the next
mail.  To do this, I needed the cwd of the compile, and
hostname printed in the logfile, otherwise it's impossible
to sort out parallel builds; a patch for this is below.

I also found the timestamp useful, but have this as a
separate patch as it may be less worth adding and it
probably needs work for portability.  I won't loose sleep
if you want to reject it.

These are against trunk.