implement I444ToABGR by swapping uv and transpose matrix

implement I444ToABGR by swapping uv and transpose matrix

U contributes to B and G.  V contributes to R and G.
By swapping U and V, they contribute to the opposite channels.  Adjust the matrix so the U contribution is in the matrix location such that it till contribute to the
new B channel and vice versa.
This allows ABGR versions of YUV conversion to use the same low level code as ARGB, just using a different matrix and swapping U and V pointers.

As a result the existing I444ToABGRRow functions are no longer needed and are removed.

Previously this function was only Intel AVX2 optimized for Windwos.  Now it is also optimized for Arm and GCC.

ARMv7 Neon
Was LibYUVConvertTest.I444ToABGR_Opt (75971 ms)
Now LibYUVConvertTest.I444ToABGR_Opt (3672 ms)
20.6 times faster.


R=xhwang@chromium.org
BUG=libyuv:515
Committed: https://chromium.googlesource.com/libyuv/libyuv/+/cf160cdbaa605c89dc15eb96f7d875ff887132e3

[xhwang, 2015-10-27 16:29:11]

Please also mention the removal of I444ToABGRRow functions in CL description.

Otherwise rs LGTM!

[fbarchard, 2015-10-27 17:21:07]

Description was changed from

==========
implement I444ToABGR by swapping uv and transpose matrix

R=xhwang@chromium.org
BUG=libyuv:515
==========

to

==========
implement I444ToABGR by swapping uv and transpose matrix

U contributes to B and G.  V contributes to R and G.
By swapping U and V, they contribute to the opposite channels.  Adjust the
matrix so the U contribution is in the matrix location such that it till
contribute to the
new B channel and vice versa.
This allows ABGR versions of YUV conversion to use the same low level code as
ARGB, just using a different matrix and swapping U and V pointers.

As a result the existing I444ToABGRRow functions are no longer needed and are
removed.

Previously this function was only Intel AVX2 optimized for Windwos.  Now it is
also optimized for Arm and GCC.

ARMv7 Neon
Was LibYUVConvertTest.I444ToABGR_Opt (75971 ms)
Now LibYUVConvertTest.I444ToABGR_Opt (3672 ms)
20.6 times faster.


R=xhwang@chromium.org
BUG=libyuv:515
==========

[fbarchard1, 2015-10-27 17:21:27]

Committed patchset #2 (id:20001) manually as
cf160cdbaa605c89dc15eb96f7d875ff887132e3 (presubmit successful).