bpo-43974: Move Py_BUILD_CORE_MODULE into module code (GH-29157)

[tiran]

setup.py no longer defines Py_BUILD_CORE_MODULE. Instead every
module defines the macro before #include "Python.h" unless
Py_BUILD_CORE_BUILTIN is already defined.

Py_BUILD_CORE_BUILTIN is defined for every module that is built by
Modules/Setup.

The PR also simplifies Modules/Setup. Makefile and makesetup
already define Py_BUILD_CORE_BUILTIN and include Modules/internal
for us.

Signed-off-by: Christian Heimes christian@python.org

https://bugs.python.org/issue43974

[vstinner]

LGTM. I compared the list of modified files to setup.py. It seems like the PR is exhausitve.

Oh. I didn't know that Modules/makesetup already uses the correct flags for build C extensions depending if it's before or after *shared* in Modules/Setup:

PY_BUILTIN_MODULE_CFLAGS= $(PY_STDMODULE_CFLAGS) -DPy_BUILD_CORE_BUILTIN PY_CORE_CFLAGS= $(PY_STDMODULE_CFLAGS) -DPy_BUILD_CORE 

[vstinner]

You may also mention Modules/Setup.

[tiran]

Oh. I didn't know that Modules/makesetup already uses the correct flags for build C extensions depending if it's before or after *shared* in Modules/Setup:

There is a problem with *shared*. I created https://bugs.python.org/issue45571 to track the issue.