External projects might run check-compliance.py from a subdirectory,
while list_undef_kconfig_refs.py expects to find the top-level Kconfig
file in the current directory.
Due to obscure Kconfig ugliness (explained in a comment), the working
directory needs to be changed here, instead of using 'srctree'.
(Thinking of changing that Kconfig behavior so that it only applies to
.config files. Suspect it's been a bug in the C tools all along for
Kconfig files.)
Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>
90e8d67848