'RELENG_4_0_0_RELEASE'.

This commit was manufactured to restore the state of the 4.0-RELEASE image.
Releases prior to 5.3-RELEASE are omitting the secure/ and crypto/ subdirs.

    madvise().

    This feature prevents the update daemon from gratuitously flushing
    dirty pages associated with a mapped file-backed region of memory.  The
    system pager will still page the memory as necessary and the VM system
    will still be fully coherent with the filesystem.  Modifications made
    by other means to the same area of memory, for example by write(), are
    unaffected.  The feature works on a page-granularity basis.

    MAP_NOSYNC allows one to use mmap() to share memory between processes
    without incuring any significant filesystem overhead, putting it in
    the same performance category as SysV Shared memory and anonymous memory.

Reviewed by: julian, alc, dg

Merge the contents (less some trivial bordering the silly comments)
of <vm/vm_prot.h> and <vm/vm_inherit.h> into <vm/vm.h>.  This puts
the #defines for the vm_inherit_t and vm_prot_t types next to their
typedefs.

This paves the road for the commit to follow shortly: change
useracc() to use VM_PROT_{READ|WRITE} rather than B_{READ|WRITE}
as argument.

since i386/i386/machdep.c rev 1.45 (or 1994 :-) ).

    syncs the entire underlying file rather then just the requested range,
    resulting in huge inefficiencies when the VM system is articulated in
    a certain way.  The VOP_FSYNC was also found to massively reduce NFS
    performance in certain cases.

    Change MADV_DONTNEED and MADV_FREE to call vm_page_dontneed() instead
    of vm_page_deactivate().  Using vm_page_deactivate() causes all
    inactive and cache pages to be recycled before the dontneed/free page
    is recycled, effectively flushing our entire VM inactive & cache
    queues continuously even if only a few pages are being actively MADV
    free'd and reused (such as occurs with a sequential scan of a
    memory-mapped file).

Reviewed by:	Alan Cox <alc@cs.rice.edu>, David Greenman <dg@root.com>

since i386/i386/machdep rev 1.310, i.e., the demise of BOUNCE_BUFFERS.

since i386/i386/pmap rev 1.190.  (The alpha never used it.)

	Update the comments to match the implementation.

Submitted by:	dillon

	Support MADV_DONTNEED and MADV_WILLNEED on object types
	besides OBJT_DEFAULT and OBJT_SWAP.

Submitted by:	dillon