package swig bindings as shared libraries

[proppy]

In order to be able to import them from .py script, the swig binding needs to be built as shared libraries.

Currently the swig_library helper forces static linking, see:
https://github.com/The-OpenROAD-Project/OpenROAD/blob/master/src/cmake/swig_lib.cmake#L74

@maliberty is the .a actually needed by something else in the build? do we need to build both or can we get away with only building the .so?

/cc @QuantamHD

[QuantamHD]

@proppy I have a demo working for one of them

[maliberty]

The .a are used to build a statically linked binary which is much simpler for users as it doesn't require setting up an LD_LIBRARY_PATH entry.

[proppy]

@maliberty understood, but curious if there a usecase for having the swig bindings openroad_swig_py.a as a static library? Is it meant for users that'd like to link and extend them?

[maliberty]

openroad -python needs the swig bindings and is statically linked.

[QuantamHD]

@proppy We need to set up the infrastructure to build and package the so's for pip.

[QuantamHD]

#2311

[maliberty]

@macd FYI

[macd]

It would be nice to be able to import into an unmodified Python. I will take a look at @QuantamHD changes (I have PoC wrappers for about 10 of the tools/libs at present). How many versions of Python do you envision building against?