fix this failure:

```
configure ... cppflags=-DMJIT_FORCE_ENABLE
...
make test-spec

1)
The -v command line option when used alone prints version and ends FAILED
Expected
"ruby 3.1.0dev (2021-12-18T10:10:42Z master 78c17528) +MJIT [x86_64-linux]
"
to include "ruby 3.1.0dev (2021-12-18T10:10:42Z master 78c17528) [x86_64-linux]"
/tmp/ruby/v3/src/trunk-mjit-wait/spec/ruby/command_line/dash_v_spec.rb:9:in `block (3 levels) in <top (required)>'
/tmp/ruby/v3/src/trunk-mjit-wait/spec/ruby/command_line/dash_v_spec.rb:4:in `<top (required)>'
```

http://ci.rvm.jp/results/trunk-mjit-wait@phosphorus-docker/3759943