Fixes: <https://issues.guix.gnu.org/52940>.
* tests/gremlin.scm (file-needed/recursive): Consider two entries to be
equivalent not when they are the same string, but rather when they refer to
the same file.
[ground-truth]: In addition to strings that begin with "linux-vdso.so", remove
strings that begin with "linux-vdso64.so".