Stop basename choking on --fakeroot in tests
Intent: keep the BSD `basename` usage text out of the `Test matrix` log.
Failure fixed: `test-matrix.sh` runs `test-proc-limits-fakeroot` with `--fakeroot` as the first argument of `run_elfuse`. That reaches `elfuse_test_host_nofile`, whose `basename "$2"` makes macOS print `basename: illegal option -- -` and its usage to stderr. The substitution fails, `$name` is empty, the manifest lookup matches nothing, and the test runs without a raised descriptor limit. The test still passes, so only the log is wrong. First seen in https://github.com/sysprog21/elfuse/actions/runs/42510136410/job/129003011498 (PR #493 CI), which passes; main has the same call.
This PR: `basename -- "$2"` in `tests/test-config.sh`.
Verified on `88d9de7`, based on `859a2d0`: `make check-format` passes (60 scripts). `elfuse_test_host_nofile tests/manifest.txt --fakeroot` returns 0 with no output, where `basename --fakeroot` fails on macOS. The full test matrix was not rerun.
Summary by cubic
Fixes basename failing on --fakeroot arguments in tests/test-config.sh on macOS, which previously produced usage output in the test log and left the manifest name empty, causing the fakeroot test to run without a raised descriptor limit. Adds -- to end option parsing so the argument is always treated as a name.