build file feature

I found some obscure references to a build file feature that allows
unlinking and therfore resource recovery from a running image. It required
an inline file in the build similar to the followng:

unlink_list={ /proc/boot/chkfsys /proc/boot/seedres /proc/boot/ifconfig
/proc/boot/route }

This no longer appears to work in 6.2. Is this capability available in some
other way in 6.2?

Thanks
Brian