new backend cmake configuration

Author: alexeyboreiko

Libraries/oneCCL/oneCCL_Getting_Started/README.md

@@ -102,7 +102,7 @@ Users can rebuild the cpu_allreduce_test.cpp by typing "make cpu_allreduce_test"
   cd oneapi-toolkit/oneCCL/oneCCL_Getting_Started
   mkdir build
   cd build
-  cmake ..  -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=dpcpp
+  cmake ..  -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=dpcpp -DCOMPUTE_BACKEND=dpcpp_level_zero
   make sycl_allreduce_test
   ```
 > NOTE: The source file "sycl_allreduce_test.cpp" will be copied from ${INTEL_ONEAPI_INSTALL_FOLDER}/ccl/latest/examples/sycl to build/src/sycl folder.

Libraries/oneCCL/oneCCL_Getting_Started/sample.json

@@ -17,7 +17,7 @@
 		"steps": [
 			"mkdir build",
       		        "cd build",
-           		"cmake .. -DCMAKE_C_COMPILER=icx -DCMAKE_CXX_COMPILER=dpcpp",
+           		"cmake .. -DCMAKE_C_COMPILER=icx -DCMAKE_CXX_COMPILER=dpcpp -DCOMPUTE_BACKEND=dpcpp_level_zero",
            		"make",
 			"mpirun -n 2 ./out/sycl/sycl_allreduce_test cpu",
 			"mpirun -n 2 ./out/sycl/sycl_allreduce_test gpu"

Libraries/oneCCL/tutorials/oneCCL_Getting_Started.ipynb

@@ -744,7 +744,7 @@
     "export EXAMPLE_ROOT=./lab/\n",
     "mkdir dpcpp\n",
     "cd dpcpp\n",
-    "cmake .. -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=dpcpp\n",
+    "cmake .. -DCMAKE_C_COMPILER=icx -DCMAKE_CXX_COMPILER=dpcpp -DCOMPUTE_BACKEND=dpcpp_level_zero\n",
     "make sycl_allreduce_cpp_test\n"
    ]
   },