This unclutters the top-level directory and groups related files together.

SPARC is no longer being used in any multimedia-related fields and the
VIS optimizations only represent a maintenance burden.

This is consistent with usual ARM nomenclature as well as with the
VFPV3 and NEON symbols which both lack the ARM prefix.
Signed-off-by: Mans Rullgard <mans@mansr.com>

The code fails to compile and is broken beyond repair.