WITHOUT_CLANG_IS_CC: There and back again

In trying to debug an unrelated problem, I switched CC from Clang
back to GCC.  I had a -current kernel and world r247050 built and
installed with Clang as the system compiler  I have nothing special
in /etc/make.conf:

   BATCH=yes
   WITH_NEW_XORG=true
   WITH_KMS=true
   WITH_PKGNG=yes
   PERL_VERSION=5.14.2

I added WITHOUT_CLANG_IS_CC=yes to this, then rebuilt kernel and
world.  I installed the kernel rebooted, everthing worked, so I
then installed world.  Installword stopped here:

   ===> libexec/rtld-elf (install)
   chflags -h noschg /usr/libexec/ld-elf.so.1
   install -s -o root -g wheel -m 555  -C -b -fschg -S ld-elf.so.1 /libexec
   install -o root -g wheel -m 444 rtld.1.gz  /usr/share/man/man1
   *** [_maninstall] Signal 11

   Stop in /opt/FreeBSD/current/src/libexec/rtld-elf.
   *** [realinstall] Error code 1

At that point my system was completely hosed.  Every binary (/bin,
/sbin, etc) would sig 11.  I had to build a world on another
system, then use /rescue to NFS mount the other system and
copy over /libexec, /lib, and /usr/lib.  This let me recover
enough to svn up to r247164. remove WITHOUT_CLANG_IS_CC from
/etc/make.conf, and build/install a working world.

Is switching from Clang to GCC suppose to work?

-- 
DE