Duplicate test class name `TestFrameVarDILPointerArithmetic` prevents
lldb-dotest from running any tests.
The conflict exists between:
- lldb/test/API/commands/frame/vardil/expr/PointerArithmetic/
- lldb/test/API/commands/frame/vardil/basics/PointerArithmetic/
Rename the expr variant to `TestFrameVarDILExprPointerArithmetic`.