Fix linking to the wrong Python library for Debug built type on Windows

[duburcqa]

No description provided.

[jorisv]

Hello @duburcqa,

Thank for the PR.
When I read wrap_python.hpp and your PR title I'm a little confuse. Did this PR allow to:

• Build our Python modules in debug mode and be loaded by a Python release runtime on Windows ?
• Build our Python module in debug mode and be loaded by a Python debug runtime on Windows ?
• Both ?

[duburcqa]

The point is rather linking with the Python library that Boost::Python wants us to link with. The current implementation in Eigenpy is by-passing Boost::Python logics entirely. Even worst, only compilation units that includes "include/eigenpy/numpy.hpp" are affected, but not the others, which means that the whole project may end up linking against multiple Python libraries at the same time.

To answer for question, it allows both, depending on whether the pragma definition "BOOST_PYTHON_DEBUG" is set. However, in practice what we want is linking with the release Python library even in debug, which is the default with Boost::Python but not with barebone Python (and hence not with numpy either).