Photo ID race condition

[Keith Ray]

There is a (non-security) race condition in the photo ID code under
Windows.  If the user has a slow loading image viewer (ie. Mozilla), GnuPG could
delete the temp file before the viewer finishes initializing.  I can think of a
number of solutions:

1. Wait for the viewer to exit before returning to GnuPG.
2. Insert a delay between exec_read() and exec_finish().  Then again, on a slow
system with little RAM, how much is enough?
3. Delay deleting the temp files until GnuPG exits.

  -- Keith