[BUG] SOP_OpenVDB_Activate.cc doesn't compile successfully with Houdini 21

Environment

Operating System: Linux Rocky 9.5
Commit SHA: 584b2b5a1b43641d54f942d981d7b50887b27d92

Describe the bug

When SOP_OpenVDB_Activate.cc was updated for Houdini 21.0's API changes, the function prototypes for inputLabel() and isRefInput() were updated to take an OP_InputIdx instead of an unsigned int, but the implementations at the bottom of the file still take unsigned int, giving a compiler error.

To Reproduce

Steps to reproduce the behavior:
Build the Houdini plugin SOP_OpenVDB_Activate.cc with Houdini 21.0.440
See the compiler error:

openvdb/openvdb_houdini/openvdb_houdini/SOP_OpenVDB_Activate.cc:1297:1: error: no declaration matches ‘const char* SOP_VDBActivate::inputLabel(unsigned int) const’
 1297 | SOP_VDBActivate::inputLabel(unsigned index) const
      | ^~~~~~~~~~~~~~~
openvdb/openvdb_houdini/openvdb_houdini/SOP_OpenVDB_Activate.cc:63:18: note: candidate is: ‘virtual const char* SOP_VDBActivate::inputLabel(OP_InputIdx) const’
   63 |     const char  *inputLabel(OP_InputIdx idx) const override;
      |                  ^~~~~~~~~~
openvdb/openvdb_houdini/openvdb_houdini/SOP_OpenVDB_Activate.cc:60:7: note: ‘class SOP_VDBActivate’ defined here
   60 | class SOP_VDBActivate : public hvdb::SOP_NodeVDB
      |       ^~~~~~~~~~~~~~~
openvdb/openvdb_houdini/openvdb_houdini/SOP_OpenVDB_Activate.cc:1310:1: error: no declaration matches ‘int SOP_VDBActivate::isRefInput(unsigned int) const’
 1310 | SOP_VDBActivate::isRefInput(unsigned i) const
      | ^~~~~~~~~~~~~~~
openvdb/openvdb_houdini/openvdb_houdini/SOP_OpenVDB_Activate.cc:64:18: note: candidate is: ‘virtual int SOP_VDBActivate::isRefInput(OP_InputIdx) const’
   64 |     int          isRefInput(OP_InputIdx i) const override;
      |                  ^~~~~~~~~~
openvdb/openvdb_houdini/openvdb_houdini/SOP_OpenVDB_Activate.cc:60:7: note: ‘class SOP_VDBActivate’ defined here
   60 | class SOP_VDBActivate : public hvdb::SOP_NodeVDB
      |       ^~~~~~~~~~~~~~~
gmake[2]: *** [openvdb_houdini/openvdb_houdini/CMakeFiles/SOP_OpenVDB_Activate.dir/build.make:79: openvdb_houdini/openvdb_houdini/CMakeFiles/SOP_OpenVDB_Activate.dir/SOP_OpenVDB_Activate.cc.o] Error 1

Start in openvdb/openvdb_houdini/openvdb_houdini/SOP_OpenVDB_Activate.cc, comparing the inputLabel() and isRefInput() declarations near lines 63–64 with their implementations near lines 1297 and 1310. Build the Houdini plugin with Houdini 21.0.440 and confirm that the compiler errors are gone.