Adjustments to MPI and NCCL library discovery on build (#4407)
Adjustments to MPI and NCCL library discovery on build (#4407)

* cmake edits for mpi_home and nccl_home

* cmake syntax error on else
microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime