I411

[Frank Barchard]

I propose removing 411 subsampling support from libyuv.

411 is 4x1 subsampling.  The code is much like 422, which is 2x1.  It was done opportunistically, since its easy to support.

Theres a bug on arm to do with odd width alignment on 411 destinations.

The bug is in the any function, and should likely be fixed as is should affect 422 as well.

But 411 is a technical debt, requiring maintainance, and as far as I know, is not used in practice.

https://code.google.com/p/libyuv/issues/detail?id=509