Remove trailing whitespace from license text

lib/spack/docs/conf.py

lib/spack/docs/exts/sphinxcontrib/__init__.py

lib/spack/docs/exts/sphinxcontrib/programoutput.py

lib/spack/spack/__init__.py

lib/spack/spack/architecture.py

lib/spack/spack/cmd/__init__.py

lib/spack/spack/cmd/arch.py

lib/spack/spack/cmd/bootstrap.py

lib/spack/spack/cmd/checksum.py

lib/spack/spack/cmd/clean.py

lib/spack/spack/cmd/compilers.py

lib/spack/spack/cmd/create.py

lib/spack/spack/cmd/doc.py

lib/spack/spack/cmd/edit.py

lib/spack/spack/cmd/fetch.py

lib/spack/spack/cmd/find.py

lib/spack/spack/cmd/graph.py

lib/spack/spack/cmd/help.py

lib/spack/spack/cmd/info.py

lib/spack/spack/cmd/install.py