[Distutils] Distutils enhancement - set variables from the command line

[Paul Moore]

It would sometimes be nice for the user to be able to customise the setup
process without having to edit setup.py. The obvious case is to allow the=
 user
to override library directories, where setup.py can assume the "normal" =
case,
but still allow for non-standard locations.

One relatively simple approach would be to write setup.py to read a
configuration file, and get such options from there. But an alternative =
option
would be to allow setup.py to have access to (part of) the command line =
typed by
the user.

My suggestion would be to allow the "global_opts" or "cmdX_opts" to =
contain
arguments of the form key=3Dvalue. These can be exposed to setup.py as a
dictionary, say distutils.args.

What do people think?

Paul.