FreeBSD 4.10 build world problem

[munn]

When I try to make buildworld after a complete cvsup (RELENG_4_10)  I am 
getting the
error

===> sendmail
make: don't know how to make freebsd.cf. Stop
*** Error code 2

When I look at /usr/src/etc/sendmail that was cvsup'd some time ago I 
see the file freebsd.cf.
If I copy that file into /usr/src/etc/sendmail, the builds completes 
successfully.

I have checked the cvsup from  freebsd2 and freebsd11 and freebsd.cf is 
not there.