include _multiprocessing/semaphore.c on win32

while building `_multiprocessing` extension
also, always build that module on win32

Author: naveen521kk

configure.ac

@@ -7447,7 +7447,7 @@ PY_STDLIB_MOD_SIMPLE([_zoneinfo])
 
 dnl multiprocessing modules
 PY_STDLIB_MOD([_multiprocessing],
-  [], [test "$ac_cv_func_sem_unlink" = "yes"],
+  [], [test "$ac_cv_func_sem_unlink" = "yes" -o "$MACHDEP" = "win32"],
   [-I\$(srcdir)/Modules/_multiprocessing])
 PY_STDLIB_MOD([_posixshmem],
   [], [test "$have_posix_shmem" = "yes"],

setup.py

@@ -1372,10 +1372,10 @@ def detect_multiprocessing(self):
         if (
             sysconfig.get_config_var('HAVE_SEM_OPEN') and not
             sysconfig.get_config_var('POSIX_SEMAPHORES_NOT_ENABLED')
-        ):
+        ) or MS_WINDOWS:
             multiprocessing_srcs.append('_multiprocessing/semaphore.c')
         self.addext(Extension('_multiprocessing', multiprocessing_srcs,
-                              libraries=(['ws2_32'] if MS_WINDOWS else None)))
+                              libraries=(['ws2_32'] if MS_WINDOWS else None), include_dirs=["Modules/_multiprocessing"]))
         self.addext(Extension('_posixshmem', ['_multiprocessing/posixshmem.c']))
 
     def detect_uuid(self):