Building a Structured Framework to Validate and Optimize Low-Level Assembly Routines in VLC

VLC contains hand-written SSE2/SSSE3 assembly for performance-critical paths but has no automated correctness testing for them. This project integrates the checkasm framework into VLC's Meson build and CI pipeline, adds test coverage for all existing assembly routines, and implements new SIMD kernels for audio/video format conversions — with initial RISC-V vector groundwork.