Use stub bfd for dynobj

[Andreas Schwab]

I'm getting a failure of ld-bootstrap on aarch64:

Executing on host: sh -c {gcc -B/opt/test/binutils/test/ld/tmpdir/gccld1/   -L/usr/aarch64-unknown-linux-gnu/lib64 -L/usr/lib64 -L/usr/local/lib64 -L/lib64 -L/usr/aarch64-unknown-linux-gnu/lib -L/usr/local/lib -L/lib -L/usr/lib     -o tmpdir/ld2 -O2 -g   -Wl,--traditional-format ldgram.o ldlex-wrapper.o lexsup.o ldlang.o mri.o ldctor.o ldmain.o plugin.o ldwrite.o ldexp.o  ldemul.o ldver.o ldmisc.o ldfile.o ldcref.o eaarch64linux.o eaarch64linuxb.o eaarch64linux32.o eaarch64linux32b.o earmelfb_linux_eabi.o earmelf_linux_eabi.o eaarch64elf.o eaarch64elf32.o eaarch64elf32b.o eaarch64elfb.o earmelf.o earmelfb.o ldelf.o ldelfgen.o ldbuildid.o ../libctf/.libs/libctf.a -lz ../bfd/.libs/libbfd.a ../libiberty/libiberty.a  ../libsframe/.libs/libsframe.a  -lz -lzstd -ldl 2>&1}  /dev/null ld.tmp (timeout = 300)
spawn [open ...]
collect2: fatal error: ld terminated with signal 4 [Illegal instruction], core dumped
compilation terminated.
collect2: fatal error: ld terminated with signal 4 [Illegal instruction], core dumped
compilation terminated.

FAIL: bootstrap with -Wl,--traditional-format

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
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