config/scripts/switch-arch: allow x86_64 prefix for x86 builds

Modern 64-bit compilers with a gcc multilib-capable toolchain are easily able
to build x86 OpenBIOS. If the build is not gcc multilib-capable then the
build typically fails with the message "fatal error: sys/cdefs.h: No such file
or directory".

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
1 file changed