kconfig/cmake: Check that one of the CONFIG_<arch> symbols is set

All SoCs must now 'select' one of the CONFIG_<arch> symbols. Add an
ARCH_IS_SET helper symbol that's selected by the arch symbols and
checked in CMake, printing a warning otherwise.

Might save people some time until they're used to the new scheme.

Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>
2 files changed