RISC-V Optimized strnlen Implementation For Linux 7.1 Yields Big Speed-Up

An optimized hand-written RISC-V Assembly implementation of strnlen() is queued for Linux 7.1, delivering up to a 427.5% performance improvement. The patch, contributed by Feng Jiang from KylinOS, includes both a generic code path and a Zbb-extension-powered variant. Additional optimized implementations of strchr() and strrchr() are also included, yielding up to 7% and 8% improvements respectively. These changes are staged in the RISC-V for-next branch ahead of the Linux 7.1 merge window.