Found non-API call to R: ‘SETLENGTH’

```
File ‘MsCoreUtils/libs/MsCoreUtils.so’:
  Found non-API call to R: ‘SETLENGTH’

Compiled code should not call non-API entry points in R.

See ‘Writing portable packages’ in the ‘Writing R Extensions’ manual,
and section ‘Moving into C API compliance’ for issues with the use of
non-API entry points.
```

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