Kill modify-python-lldb.py

Summary:
After the last round of cleanups, this script was almost a no-op. The
only piece of functionality that remained was the one which tried to
make the swig-generated function signatures more pythonic.

The "tried" part is important here, as it wasn't doing a really good job
and the end result was not valid python nor c (e.g.,
SetExecutable(SBAttachInfo self, str const * path)).

Doing these transformations another way is not possible, as these
signatures are generated by swig, and not present in source. However,
given that this is the only reason why we need a swig post-process step,
and that the current implementation is pretty sub-optimal, this patch
simply abandons the signature fixup idea, and chooses to simplify our
build process instead.

Reviewers: amccarth, jingham, clayborg

Subscribers: mgorny, lldb-commits

Differential Revision: https://reviews.llvm.org/D61000

llvm-svn: 359092