Port config.guess to strict POSIX.1-2024 c17 * config.guess (set_cc_for_build): Try the c17 compiler, standardized in POSIX.1-2024. See: https://pubs.opengroup.org/onlinepubs/9799919799/utilities/c17.html While we're at it, prefer c99 to c89. Signed-off-by: Dmitry V. Levin <[email protected]>