Fix gcc2 build.
BColumnListView: Enable invalidating rows, fix SetField()

 * Seems like there was no easy way to simply invalidate
   a given BRow. Introduced BColumnListView::InvalidateRow().
 * BRow::SetField() tried to invalidate the row, but invalidated
   the listview instead of the BOutlineView responsible for
   drawing the list contents. Use the new InvaalidateRow().
HaikuDepot: Update package list when necessary

 * Pass the Model lock to the PackageListView.
 * Register a PackageInfoListener with every listed package.
 * Update the rating when it is fetched.
libroot: Make sure PTHREAD_STACK_MIN is in the allowed range
system: Use B_PAGE_SIZE to define stack sizes

As korli suggested use B_PAGE_SIZE for defining stack size related
definitions what seems to be more natural for them  and also may
help if we ever support an architecture with page size different than
4kB.
posix: Update PTHREAD_STACK_MIN to match MIN_USER_STACK_SIZE

Thanks for pointing this out Pete!