Reorder mm_context_t to remove alignment padding on 64 bit
builds shrinking its size from 64 to 56 bytes.

This allows mm_struct to shrink from 840 to 832 bytes, so using
one fewer cache lines, and getting more objects per slab when
using slub.

slabinfo mm_struct reports
before :-

    Sizes (bytes)     Slabs
    -----------------------------------
    Object :     840  Total  :       7
    SlabObj:     896  Full   :       1
    SlabSiz:   16384  Partial:       4
    Loss   :      56  CpuSlab:       2
    Align  :      64  Objects:      18

after :-

    Sizes (bytes)     Slabs
    ----------------------------------
    Object :     832  Total  :       7
    SlabObj:     832  Full   :       1
    SlabSiz:   16384  Partial:       4
    Loss   :       0  CpuSlab:       2
    Align  :      64  Objects:      19

Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
Cc: wilsons@start.ca
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Link: http://lkml.kernel.org/r/1306244999.1999.5.camel@castor.rsk
Signed-off-by: Ingo Molnar <mingo@elte.hu>

This tag is intended to mirror the thread info TIF_IA32 flag.  Will be used to
identify mm's which support 32 bit tasks running in compatibility mode without
requiring a reference to the task itself.

Signed-off-by: Stephen Wilson <wilsons@start.ca>
Reviewed-by: Michel Lespinasse <walken@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Change header guards named "ASM_X86__*" to "_ASM_X86_*" since:

a. the double underscore is ugly and pointless.
b. no leading underscore violates namespace constraints.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>