change name of files which pass rspec regression test on master

This PR is related to #2174. This change adds *_spec* to name of files which pass rspec regression test on master.

### Rake task
```
jruby bin/rake spec:regression
```
### Results
Before: on master(cab9b48065122053f4f4d21a26f81c53b7eb7498)
```
309 examples, 0 failures
```
After: on master(b946dee5b6d5a3665c0d64af48db594fef626032)
```
315 examples, 0 failures, 1 pending

Pending:
  A file required from a load path entry with an embedded symlink leaves LOADED_FEATURES unexpanded
    # fix for #1941
    # ./spec/regression/GH-1940_symlink_load_path_should_not_expand_in_FILE_spec.rb:30
```