Not sure about the kernel config error, theh only thing that comes to my mind is - try running config process manually by running "bitbake -c devshell linux-yocto-clanton", this will drop you in a shell with prepared environment where you can then run "make oldconfig" and other standard kernel config/compile commands. Maybe you'll be able to extract some more information that way.
These
There are also a bnuch of warnings like this:
NOTE: consider defining a PREFERRED_PROVIDER entry to match glibc-gconv-ibm850-native
NOTE: multiple providers are available for runtime glibc-gconv-ibm437-native (eglibc-locale, nativesdk-eglibc-locale)
The number after ibm varies. How can I fix this?
are harmless, if that's what you mean, so you can simply ignore them. If your goal is namely to get rid of them - then I've no idea, sorry, haven't pursued that, just always ignored