Earlier you wrote something which really doesn't fit in your scheme :
>>> On GNU/Linux crti.o comes from glibc, not gcc. It is normally found
>>> in /usr/lib.
>> On my system that file resides in /usr/lib64/crti.o.
So, where is this file, in the "native old root system" or in your new
chroot'ed self-made system? Of course in your self-made system the
'$LFS/usr/lib64/crti.o' would be the component, from the self-made
glibc and the new chroot'ed GCC should find and use it, not the Gentoo
one in '/usr/lib64'.