Add arm64 version of OpenVDB to CMake module path. (#306)

Author: agoeckner

openvdb_vendor/openvdb_vendor-extras.cmake

@@ -5,4 +5,5 @@ endif()
 message( STATUS "CMAKE_BUILD_TYPE: ${CMAKE_BUILD_TYPE}" )
 list(APPEND CMAKE_MODULE_PATH "${openvdb_vendor_DIR}/../../../opt/openvdb_vendor/lib/cmake/OpenVDB")
 list(APPEND CMAKE_MODULE_PATH "/usr/lib/x86_64-linux-gnu/cmake/OpenVDB")
+list(APPEND CMAKE_MODULE_PATH "/usr/lib/aarch64-linux-gnu/cmake/OpenVDB")
 find_package(OpenVDB REQUIRED)