A couple of setup.exe nits

[Jason Tishler]

I found the following nits with the current setup.exe:

1. setup.exe no longer responds to Windows messages during postinstall.

I noticed this because one of my postinstall scripts did a
SendMessage(HWND_BROADCAST, ...) which caused a deadlock situation.
I changed to PostMessage() to workaround the problem.  Note that Task
Manager also indicates a status of "Not Responding".

2. /etc/setup/installed.db indicates files end with ".bz2" regardless of
   their true suffix.

I don't know if this will cause problems or not, but I found it
disconcerting.

Jason