CURRENT (r249438): (devel/libiconv)./unistd.h:686:5: error: invalid token at start of a preprocessor expression : #if @GNULIB_EUIDACCESS@

Trying to recompile converters/libiconv on FreeBSD 10.0-CUR/r49438 (with
bran new CLANG 3.3) results  with the errors below. This error shows up
on boxes having FBSD 10 and X11. It doesn't show up on those boxes
running without a full X11 (that is the only difference I can figure out
at the moment since the different systems share a lot of configuration
stuff, having different CPU types (C2D, Sandy-Bridge, Ivy-Bridge) but
nothing I can figure out as the source of the strange behaviour and
error).

Maybe someone has a hint what this could be ...

Thanks in advance and regards,
Oliver

converters/libiconv:

[...]
rm -f unitypes.h-t unitypes.h &&  { echo '/* DO NOT EDIT! GENERATED
AUTOMATICALLY! */';  cat ./unitypes.in.h;  } > unitypes.h-t &&  mv -f
unitypes.h-t unitypes.h
rm -f uniwidth.h-t uniwidth.h &&  { echo '/* DO NOT EDIT! GENERATED
AUTOMATICALLY! */';  cat ./uniwidth.in.h;  } > uniwidth.h-t &&  mv -f
uniwidth.h-t uniwidth.h
make  all-am
cc -DHAVE_CONFIG_H -DEXEEXT=\"\" -I. -I.. -I../lib  -I../intl
-DDEPENDS_ON_LIBICONV=1  -DDEPENDS_ON_LIBINTL=1    -O2 -pipe -O3
-march=native -fno-strict-aliasing -c allocator.c
cc -DHAVE_CONFIG_H -DEXEEXT=\"\" -I. -I.. -I../lib  -I../intl
-DDEPENDS_ON_LIBICONV=1  -DDEPENDS_ON_LIBINTL=1    -O2 -pipe -O3
-march=native -fno-strict-aliasing -c areadlink.c
In file included from areadlink.c:27:
In file included from ./careadlinkat.h:23:
In file included from ./fcntl.h:62:
./unistd.h:694:5: error: invalid token at start of a preprocessor
expression
#if _at_GNULIB_EUIDACCESS_at_
    ^
1 error generated.
*** [areadlink.o] Error code 1

Stop in /usr/ports/converters/libiconv/work/libiconv-1.14/srclib.
*** [all] Error code 1

Stop in /usr/ports/converters/libiconv/work/libiconv-1.14/srclib.
*** [all] Error code 1

Stop in /usr/ports/converters/libiconv/work/libiconv-1.14.
*** [do-build] Error code 1

Stop in /usr/ports/converters/libiconv.
*** [install] Error code 1

Stop in /usr/ports/converters/libiconv.
*** [reinstall] Error code 1

Stop in /usr/ports/converters/libiconv.