fix android roll

Guarding loads of 8-15 with defined(__AVX2__) should prevent errors
like these:

    external/skia/src/jumper/SkJumper_stages_lowp.cpp:287:46: error:
    'memcpy' called with size bigger than buffer
            case 12: memcpy(&v, ptr, 12*sizeof(T)); break;

The loads of 8-15 were of course unreachable, given the &(N-1) == &7.

Change-Id: Ifcb5c177c6909e1df55cb564779a4d6610ff7b32
Reviewed-on: https://skia-review.googlesource.com/46521
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Mike Klein <mtklein@chromium.org>
3 files changed