Collection of warnignfixes for 2.4.0test3-pre2

[Arjan van de Ven]

Hi,

The -Werror flag in 2.4.0test3-pre2 showed a lot of warings; most of them
are of the "unused" kind, but several of them are more severe and show
actual bugs.

I fixed all "non-unused" ones I could find; the patch (21Kb) for this is
at 

http://www.fenrus.demon.nl/warnings.diff

Once Linus puts out test3-pre3 I'll resync and send him the rest.

Greetings,
   Arjan van de Ven