[gcc installation] Wrapped cxx files produce lots of warnings: "_POSIX_C_SOURCE" redefined

[opeil]

The problem can be traced back to "mako/wrap.cxx". With pure gcc compilation (without clang) #include involves include from "/usr/include/features.h", which conflicts with Python.h.

Also, in its current form "mako/wrap.cxx" does not follow the recommendation for TRIQS users: https://triqs.github.io/triqs/master/reference/utilities/python_include_mess.html

"#include <cpp2py.hpp>" should go first.

================= mako/wrap.cxx ==================
#include
#include
#include //for std::cout...
using dcomplex = std::complex;

// first the basic stuff
#include <cpp2py.hpp>
.......

[opeil]

Moreover, in cpp2py.hpp #include "cpp2py/pyref.hpp" should be placed first and "#include " should be added after #include <Python.h>.