* vm_copy_on_write_area() now does no longer overwrite the ref_count, but keeps
it's reference to the cache until it has unlocked it.
* It now also locks its reference from the start, preventing any other thread
to interfere.
* vm_cache_remove_consumer() now detects if it has to remove a foreign busy
page itself in order to preserve a mapped page.
* vm_soft_fault() now keeps a reference to the cache that owns the page to be
mapped until it has actually mapped it.
* vm_unmap_pages() removed the mappings of all pages of the area instead of only
those that are within the requested range.
* Kept (disabled) debug output for convenience.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@21482 a95241bf-73f2-0310-859d-f6bbb57e9c96
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