config: enable DEBUG_INFO_BTF
    
    This was disabled when the option was introduced in 5.2-rc1 but it turned
    out there are interesting use cases for having it enabled.
    
    Add pahole to build time dependencies as it is used to extracth the BTF
    data. Once we figure out how to make it conditional (only if DEBUG_INFO_BTF
    exists and is enabled), it should be done in packaging branch.