This partially reverts commits 1fc2a47f0b6c415312593e43489cf9ea2507d902 and 9816e726e747d72e0c5ac92aa20e652031a10448.
See D109727. Replacing config.guess in favor of {gcc,clang} -dumpmachine
can avoid the riscv64-{redhat,suse}-linux GCC detection.
Acked-by: Luís Marques <luismarques@lowrisc.org>