1.6.0
  - Windows: update to protobuf 21.12

1.5.0
  - Windows: upgrade to libprotobuf 3.19.4
  - No longer force CXX11 (use local C++ default std)

1.4.4
  - Compile with CXX17 if available (needed for recent libprotobuf)

1.4.3
  - Update libcld3 from upstream (fixes CRAN compiler warning)

1.4.2
  - Windows: fix rwinlib ucrt libs

1.4.1
  - Fix typo in configure script

1.4
  - Use CXX11 in configure script, needed by protobuf 3.14
  - Do not use bash in configure script

1.3
  - Fix for CRAN: do not use CXXCPP

1.2
  - Windows: update to protobuf 3.8.0 with support for GCC 8+
  - Suppress warnings about pragmas in autogenerated protobuf headers

1.1
  - Windows: update to protobuf 3.5.1 (to support gcc 8.1.0 toolchain)