Added python script to support running pylint.

See the script comments for how to modify your
pylintrc file (e.g. $HOME/.pylintrc) to support
always finding the lldb-specific Python library
directories.

With the pylintrc modification using this script,
the lldb python tests and test inferstructure can
be linted on any of potentially multiple lldb source
trees on the system without further work from
the developer.  

llvm-svn: 248676