Please update config.guess to support RISC-V

Hi, I'm building Bind9 on RISC-V. However, I met some error when executing ./configure in unpacked release tarball.

checking whether to enable maintainer-specific portions of Makefiles... yes
checking build system type... ./config.guess: unable to guess system type

This script, last modified 2015-01-01, has failed to recognize
the operating system you are using. It is advised that you
download the most up to date version of the config scripts from

  http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess;hb=HEAD
and
  http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.sub;hb=HEAD

If the version you run (./config.guess) is already up to date, please
send the following data and any information you think might be
pertinent to <config-patches@gnu.org> in order to provide the needed
information to handle your system.

config.guess timestamp = 2015-01-01

uname -m = riscv64
uname -r = 5.15.10+
uname -s = Linux
uname -v = #1 SMP Fri Dec 24 14:24:27 CST 2021

/usr/bin/uname -p = unknown
/bin/uname -X     = 

hostinfo               = 
/bin/universe          = 
/usr/bin/arch -k       = 
/bin/arch              = 
/usr/bin/oslevel       = 
/usr/convex/getsysinfo = 

UNAME_MACHINE = riscv64
UNAME_RELEASE = 5.15.10+
UNAME_SYSTEM  = Linux
UNAME_VERSION = #1 SMP Fri Dec 24 14:24:27 CST 2021
configure: error: cannot guess build type; you must specify one

As far as I know, a more recent version of config.guess can recognize RISC-V. So could you please update config.guess and config.sub to support RISC-V?