[cindex.py] Make CompileCommand.arguments usage consistent with CompileCommand.directory and the rest of the python binding

Patch by David Röthlisberger

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@159970 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed