More signedness tweaks to chunk allocator.
More signedness tweaks to chunk allocator.

darcs-hash:20080907225346-4cc09-053616020e9cc375264cfa5451460e4ed8705226.gz

strongwillow/polipo,dxq-git/polipo,fqtools/polipo,Psiphon-Inc/polipo,nxtreaming/chumen,fqtools/polipo,jeromelebel/polipo,jech/polipo,doublec/namecoin-polipo,berkley4/polipo,fukusaka/polipo,toke/polipo,TierraDelFuego/opilop,galeksandrp/polipo,jech/polipo,ssb22/polipo2,clowwindy/polipo,Android-Apps/polipo,feijilei/polipo,ssb22/polipo2,berkley4/polipo,galeksandrp/polipo,danchr/polipo,lkraider/polipo,lkraider/polipo,feijilei/polipo,feijilei/polipo,akkakks/polipo,dxq-git/polipo,akkakks/polipo,gorakhargosh/polipo,berkley4/polipo,Android-Apps/polipo,lkraider/polipo,nxtreaming/chumen,galeksandrp/polipo,caeies/polipo-caeies,akkakks/polipo,jech/polipo,dxq-git/polipo,fqtools/polipo,ssb22/polipo2,ajmgh/polipo,nxtreaming/chumen,strongwillow/polipo