Memory leak fixes in setupdb and setup

[Stephane Peter]

I just committed a bunch of fixes to memory management in both 
loki_setupdb and loki_setup. Basically the root of this problem is that 
in libxml, xmlGetProp() returns a malloced string, that needs to be 
explicitly deallocated. This just came to my attention recently when 
running valgrind on some of my projects, and I started to clean up 
setup as well.

Unfortunately we really abuse this function all over the code. Setupdb 
should be mostly clean now, but loki_setup is going to be a royal pain 
to fix. I only fixed the most easy functions so far. On the other hand, 
the urge is not too strong since it's an installer and the user usually 
doesn't have time to notice the leaks...

Anyway, if you notice any weirdness in the current CVS snapshot, please 
let me know.

--
Stéphane Peter
megastep at megastep.org