bpo-20104: Remove posix_spawn from 3.7 (GH-6794)

Remove os.posix_spawn, the API isn't complete and we're still figuring out how it should look. wait for 3.8.
diff --git a/Modules/clinic/posixmodule.c.h b/Modules/clinic/posixmodule.c.h
index e4bbd08..ab1f753 100644
--- a/Modules/clinic/posixmodule.c.h
+++ b/Modules/clinic/posixmodule.c.h
@@ -1727,54 +1727,6 @@
 
 #endif /* defined(HAVE_EXECV) */
 
-#if defined(HAVE_POSIX_SPAWN)
-
-PyDoc_STRVAR(os_posix_spawn__doc__,
-"posix_spawn($module, path, argv, env, file_actions=None, /)\n"
-"--\n"
-"\n"
-"Execute the program specified by path in a new process.\n"
-"\n"
-"  path\n"
-"    Path of executable file.\n"
-"  argv\n"
-"    Tuple or list of strings.\n"
-"  env\n"
-"    Dictionary of strings mapping to strings.\n"
-"  file_actions\n"
-"    A sequence of file action tuples.");
-
-#define OS_POSIX_SPAWN_METHODDEF    \
-    {"posix_spawn", (PyCFunction)os_posix_spawn, METH_FASTCALL, os_posix_spawn__doc__},
-
-static PyObject *
-os_posix_spawn_impl(PyObject *module, path_t *path, PyObject *argv,
-                    PyObject *env, PyObject *file_actions);
-
-static PyObject *
-os_posix_spawn(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
-{
-    PyObject *return_value = NULL;
-    path_t path = PATH_T_INITIALIZE("posix_spawn", "path", 0, 0);
-    PyObject *argv;
-    PyObject *env;
-    PyObject *file_actions = Py_None;
-
-    if (!_PyArg_ParseStack(args, nargs, "O&OO|O:posix_spawn",
-        path_converter, &path, &argv, &env, &file_actions)) {
-        goto exit;
-    }
-    return_value = os_posix_spawn_impl(module, &path, argv, env, file_actions);
-
-exit:
-    /* Cleanup for path */
-    path_cleanup(&path);
-
-    return return_value;
-}
-
-#endif /* defined(HAVE_POSIX_SPAWN) */
-
 #if (defined(HAVE_SPAWNV) || defined(HAVE_WSPAWNV))
 
 PyDoc_STRVAR(os_spawnv__doc__,
@@ -6194,10 +6146,6 @@
     #define OS_EXECVE_METHODDEF
 #endif /* !defined(OS_EXECVE_METHODDEF) */
 
-#ifndef OS_POSIX_SPAWN_METHODDEF
-    #define OS_POSIX_SPAWN_METHODDEF
-#endif /* !defined(OS_POSIX_SPAWN_METHODDEF) */
-
 #ifndef OS_SPAWNV_METHODDEF
     #define OS_SPAWNV_METHODDEF
 #endif /* !defined(OS_SPAWNV_METHODDEF) */
@@ -6589,4 +6537,4 @@
 #ifndef OS_GETRANDOM_METHODDEF
     #define OS_GETRANDOM_METHODDEF
 #endif /* !defined(OS_GETRANDOM_METHODDEF) */
-/*[clinic end generated code: output=8d3d9dddf254c3c2 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=c966c821d557b7c0 input=a9049054013a1b77]*/