IBM Linux on z SIMD optimization

Is your feature request related to a problem? Please describe. IBM z architecture provides SIMD capabilities that can be utilized for zstd optimization similar to SSE and Neon SIMD optimizations that have been contributrd to zstd.

Describe the solution you'd like Optimize zstd to utilize IBMz VX SIMD intrinsics in zstd_lazy.c and ztsd_compress.c equivalent to optimization for SSE and Neon.

Describe alternatives you've considered Because zstd has implemented architecture-specific optimizations for other architectures, a hand-coded implementation has been shown to provide unique benefits above auto-vectorization.

Additional context Financial bounty from IBM available for negotiation. Inquiries from interested developers welcome.