Use the 21.08 branch of rapids-cmake as rmm requires it (#278)

Now that `rmm` uses `rapids-cmake` we need to update to the `21.08` branch to get the new `rapids_cmake_write_version_file` function

Authors:
  - Robert Maynard (https://github.com/robertmaynard)

Approvers:
  - Dante Gama Dessavre (https://github.com/dantegd)

URL: #278

cpp/CMakeLists.txt

@@ -19,7 +19,7 @@ include(FetchContent)
 FetchContent_Declare(
   rapids-cmake
   GIT_REPOSITORY https://github.com/rapidsai/rapids-cmake.git
-  GIT_TAG        origin/branch-21.06
+  GIT_TAG        origin/branch-21.08
   )
 FetchContent_MakeAvailable(rapids-cmake)
 include(rapids-cmake)
@@ -104,6 +104,7 @@ endif(NOT DISABLE_OPENMP OR NOT ${DISABLE_OPENMP})
 # add third party dependencies using CPM
 rapids_cpm_init()
 
+include(cmake/thirdparty/get_thrust.cmake)
 include(cmake/thirdparty/get_rmm.cmake)
 include(cmake/thirdparty/get_cuco.cmake)
 

cpp/cmake/thirdparty/get_thrust.cmake

@@ -0,0 +1,30 @@
+# =============================================================================
+# Copyright (c) 2021, NVIDIA CORPORATION.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+# in compliance with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software distributed under the License
+# is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+# or implied. See the License for the specific language governing permissions and limitations under
+# the License.
+# =============================================================================
+
+# Use CPM to find or clone thrust
+function(find_and_configure_thrust VERSION)
+
+  rapids_cpm_find(
+    Thrust ${VERSION}
+    BUILD_EXPORT_SET raft-exports
+    INSTALL_EXPORT_SET raft-exports
+    CPM_ARGS
+    GIT_REPOSITORY https://github.com/NVIDIA/thrust.git
+    GIT_TAG ${VERSION}
+    GIT_SHALLOW TRUE
+    OPTIONS "THRUST_INSTALL OFF")
+
+endfunction()
+
+find_and_configure_thrust(1.12.0)