This is more consistent with the way we handle C #includes and
it simplifies the build system.

This is necessary to allow refactoring some x86util macros with cpuflags.

Add support for all x86-64 registers
Prefer caller-saved register over callee-saved on WIN64
Support up to 15 function arguments

Also (by Ronald S. Bultje)
Fix up our asm to work with new x86inc.asm.
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
Signed-off-by: Justin Ruggles <justin.ruggles@gmail.com>

Fixes overflows for large image sizes.

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org

This allows combining multiple conditionals in a single statement.

scale.asm keeps horizontal scaling functions, whereas output.asm gets
the vertical scaling/output functions.

The issue had been introduced in
c4356536Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

This fixes assembling using "nasm".

Also implement MMX/MMX2 versions and SSE4 versions.

Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>

The intermediate buffer is always aligned.

Speed: from 3.9x to 9.6x speed improvement over C, and some small
(up to 15%) speed improvements over existing MMX code (particularly
for bigger filters).