Package check result: NOTE

Check: compiled code, Result: NOTE
  File ‘qs/libs/qs.so’:
    Found non-API calls to R: ‘FRAME’, ‘HASHTAB’, ‘LEVELS’, ‘PRENV’,
      ‘SETLEVELS’, ‘SET_CLOENV’, ‘SET_ENCLOS’, ‘SET_FRAME’,
      ‘SET_HASHTAB’, ‘SET_PRENV’, ‘SET_S4_OBJECT’, ‘SET_TRUELENGTH’
  
  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.

No changes to worse in reverse depends.