I tried to follow the instructions as closely as possible and get
ar rc ./libiberty.a \
./regex.o ./cplus-dem.o ./cp-demangle.o ./md5.o ./sha1.o ./alloca.o ./argv.o ./choose-temp.o ./concat.o ./cp-demint.o ./crc32.o ./dyn-string.o ./fdmatch.o ./fibheap.o ./filename_cmp.o ./floatformat.o ./fnmatch.o ./fopen_unlocked.o ./getopt.o ./getopt1.o ./getpwd.o ./getruntime.o ./hashtab.o ./hex.o ./lbasename.o ./lrealpath.o ./make-relative-prefix.o ./make-temp-file.o ./objalloc.o ./obstack.o ./partition.o ./pexecute.o ./physmem.o ./pex-common.o ./pex-one.o ./pex-unix.o ./safe-ctype.o ./simple-object.o ./simple-object-coff.o ./simple-object-elf.o ./simple-object-mach-o.o ./sort.o ./spaces.o ./splay-tree.o ./strerror.o ./strsignal.o ./unlink-if-ordinary.o ./xatexit.o ./xexit.o ./xmalloc.o ./xmemdup.o ./xstrdup.o ./xstrerror.o ./xstrndup.o ./setproctitle.o; \
ranlib ./libiberty.a; \
cd ..; \
else true; fi
make[3]: Leaving directory `/home/xxx/gdc_building/gdc/dev/gcc-4.6.1/objdir/build-i686-pc-linux-gnu/libiberty'
make[2]: Leaving directory `/home/xxx/gdc_building/gdc/dev/gcc-4.6.1/objdir'
make[1]: *** [stage1-bubble] Error 2
make[1]: Leaving directory `/home/xxx/gdc_building/gdc/dev/gcc-4.6.1/objdir'
make: *** [all] Error 2