Remove unused "neon" labels and mark external function as "extern"
Add some comments to macro assembly
Optionally define SSE constants in header
YASM is no longer needed to build for Windows
Define externals only when needed
Merge commit '869efff02080d23cfea2b4c1aa79fc8d7de5bb44'
Disable type cast warning from data pointer to function pointer
Merge commit 'af8d306ec3eb4bac01af536bda2d88743ae2559c'