Meson has a defined list of known CPU families but these are not currently
validated, so mistakes in cross files or new architectures are not noticed.
Backport a patch from upstream which warns on unknown architectures, but tweak
it to fatally error instead. When we upgrade to Meson 0.47 the first half of
this patch can be dropped.
Signed-off-by: Ross Burton <ross.burton@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
