ctfconvert again

[George Mitchell]

So I updated my FreeBSD machine to 9.1-RELEASE in the hope of getting
past the ctfconvert problem that causes a build of 10-CURRENT to say:

ERROR: ctfconvert: failed to initialize DWARF: Unimplemented code at 
[dwarf_init_attr(400)]

while compiling every kernel source file.  Then I checked out head as
of 245422 into a different partition and tried "make buildworld" (ran
okay) and "make buildkernel" (failed with the same error as before).

Do I have to build an early version of head before I can build the
current version of head?                          -- George Mitchell