Changes in version 2.1-9 (2025-11-10)                  

  - replace EXTPTR_PTR with R_ExternalPtrAddr
  - replace EXTPTR_TAG with R_ExternalPtrTag

                 Changes in version 2.1-8 (2023-01-24)                  

  - Corrections to configure and configure.ac kindly provided by Kurt
    Hornik