As you see in the sequence there are two configure && make calls
mkdir binutils-build && cd binutils-build
../binutils-gdb/configure && make -j8
# ^^^^^^^^^ this ones builds bfd and some other stuff
mkdir gold && cd gold
../../binutils-gdb/gold/configure && make check-TESTS
# ^^^^^^^^ and this one builds gold and runs the tests.
But as Frans wrote, the tests are passing. We have to construct a more
complex test case.
I tried building helloworld.c with bfd and gold, and they both work.
So the bug must be really not that obvious as I hoped.