Remove libcudacxx patch needed for nvcc 11.4 (#446)

The `libcudacxx.patch` was required to fix issues with libcudacxx 1.6 and incorrect detection of the arm nvcc 11.4 compiler.

As rapids-cmake has moved to libcudacxx 1.7 this patch is not needed, and should be removed.

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

Approvers:
  - Corey J. Nolet (https://github.com/cjnolet)

URL: #446

cpp/cmake/thirdparty/get_libcudacxx.cmake

@@ -16,10 +16,7 @@
 function(find_and_configure_libcudacxx)
   include(${rapids-cmake-dir}/cpm/libcudacxx.cmake)
 
-  rapids_cpm_libcudacxx(
-    BUILD_EXPORT_SET raft-exports INSTALL_EXPORT_SET raft-exports PATCH_COMMAND patch
-    --reject-file=- -p1 -N < ${RAFT_SOURCE_DIR}/cmake/libcudacxx.patch || true
-  )
+  rapids_cpm_libcudacxx(BUILD_EXPORT_SET raft-exports INSTALL_EXPORT_SET raft-exports)
 
 endfunction()