21991e6ca5 enables `__builtin_assume()` for clang and it seems
skip SEGV on rb_class_of() with unexpected value. This test expects
a [BUG] output, so this patch causes [BUG] to show [BUG] message.
707088232 (step):12:230
```
1) Failure:
TestVMDump#test_darwin_invalid_access [/Users/runner/runners/2.262.1/work/ruby/ruby/src/test/ruby/test_vm_dump.rb:19]:
pid 43128 exit 0.
1. [2/2] Assertion for "stderr"
| Expected /^\[IMPORTANT\]/ to match "".
```
* test/ruby/test_vm_dump.rb (assert_darwin_vm_dump_works): gcc seems
not to chain some frames like Apple's clang.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61291 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
