pkinit debugging

[Kevin Coffman]

We currently use printf to print debugging information.  It is enabled
by compiling with -DDEBUG.  Without this defined, if something goes
wrong with pkinit you get get a password prompt with no clue on what
went wrong with pkinit.

I'd like to propose a new runtime option to enable the debugging
messages to be printed somewhere so that problems can be diagnosed
without the need to re-compile with -DDEBUG.

I was thinking about something like "-X debug[= [stdout | stderr |
<filename> ]]".  There could also be a debugging level option if that
seems desirable.  By sending debug output to a file, non-interactive
logins from pam could also be debugged.

Any suggestions?

K.C.