Add workaround for missing riscv_hwprobe syscall (258)

Add workaround for missing riscv_hwprobe syscall (258)

On riscv newer glibc (2.41) will probe instruction support using the
riscv_hwprobe syscall. Since Valgrind currently doesn't have a wrapper
for riscv_hwprobe that causes a Warning. Since the RISC-V Hardware
Probing Interface is non-trivial and we don't really implement
extended riscv instructions anyway work around that by "implementing"
riscv_hwprobe as sys_ni_syscall so it generates an ENOSYS and glibc
will silently fall back to not using any extended instructions.

https://docs.kernel.org/arch/riscv/hwprobe.html

https://bugs.kde.org/show_bug.cgi?id=503253