cmake: Execute arch/CMakeLists.txt before subsys/CMakeList.txt

Re-order the execution of the arch/ and subsys/ CMakeLists.txt code to
work around a manifestation of issue #6505. When OpenThread created an
External project in subsys, it did not have access to important
toolchain flags added in arch/.

Intuitively, subsystems might depends on how the ARCH is configured,
but the ARCH shouldn't depend on any subsystem.

Signed-off-by: Sebastian Bøe <sebastian.boe@nordicsemi.no>
1 file changed