vm_cache_ref starts with a reference count of 1. When acquiring a vm_cache,
you no longer need to worry if that should go through the vm_store, or not;
as it now always does.
* map_backing_store() no longer needs to play with the vm_cache_ref
references.
* that simplified some code.
* vfs_get_vnode_cache() now grabs a reference to the cache, if successful.
* better balanced vnode ownership on vnode_store creation (vnode_store
released the vnode before if its creation failed).
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@15641 a95241bf-73f2-0310-859d-f6bbb57e9c96
ea2cd27e57