Add tests for the interaction between BUILD_EXCLUSIVE options

[evelikov]

As mentioned earlier #314 (comment) it would be great if we get a bit of coverage about the interaction between different BUILD_EXCLUSIVE options. The link covers the kernel/kernel_min/kernel_max combination.

With #269 we introduce another option BUILD_EXCLUSIVE_CONFIG which should be covered as well. Off the top of my head, the following will be enough:

• "CONFIG_FOO"
• "!CONFIG_FOO"
• "CONFIG_FOO !CONFIG_FOO" - user error, we should warn/error in this case