gh-110964: Remove private _PyArg functions (#110966)

Move the following private functions and structures to
pycore_modsupport.h internal C API:

* _PyArg_BadArgument()
* _PyArg_CheckPositional()
* _PyArg_NoKeywords()
* _PyArg_NoPositional()
* _PyArg_ParseStack()
* _PyArg_ParseStackAndKeywords()
* _PyArg_Parser structure
* _PyArg_UnpackKeywords()
* _PyArg_UnpackKeywordsWithVararg()
* _PyArg_UnpackStack()
* _Py_ANY_VARARGS()

Changes:

* Python/getargs.h now includes pycore_modsupport.h to export
  functions.
* clinic.py now adds pycore_modsupport.h when one of these functions
  is used.
* Add pycore_modsupport.h includes when a C extension uses one of
  these functions.
* Define Py_BUILD_CORE_MODULE in C extensions which now include
  directly or indirectly (via code generated by Argument Clinic)
  pycore_modsupport.h:

  * _csv
  * _curses_panel
  * _dbm
  * _gdbm
  * _multiprocessing.posixshmem
  * _sqlite.row
  * _statistics
  * grp
  * resource
  * syslog

* _testcapi: bad_get() no longer uses METH_FASTCALL calling
  convention but METH_VARARGS. Replace _PyArg_UnpackStack() with
  PyArg_ParseTuple().
* _testcapi: add PYTESTCAPI_NEED_INTERNAL_API macro which is defined
  by _testcapi sub-modules which need the internal C API
  (pycore_modsupport.h): exceptions.c, float.c, vectorcall.c,
  watchers.c.
* Remove Include/cpython/modsupport.h header file.
  Include/modsupport.h no longer includes the removed header file.
* Fix mypy clinic.py

Modules/_sqlite/clinic/_sqlite3.connect.c.h

@@ -6,6 +6,7 @@ preserve
 #  include "pycore_gc.h"          // PyGC_Head
 #  include "pycore_runtime.h"     // _Py_ID()
 #endif
+#include "pycore_modsupport.h"    // _PyArg_UnpackKeywords()
 
 PyDoc_STRVAR(pysqlite_connect__doc__,
 "connect($module, /, database, timeout=5.0, detect_types=0,\n"
@@ -27,4 +28,4 @@ PyDoc_STRVAR(pysqlite_connect__doc__,
 
 #define PYSQLITE_CONNECT_METHODDEF    \
     {"connect", _PyCFunction_CAST(pysqlite_connect), METH_FASTCALL|METH_KEYWORDS, pysqlite_connect__doc__},
-/*[clinic end generated code: output=03bd99542e3aec9d input=a9049054013a1b77]*/
+/*[clinic end generated code: output=69b9b00da71c3c0a input=a9049054013a1b77]*/

Modules/_sqlite/clinic/blob.c.h

@@ -2,6 +2,8 @@
 preserve
 [clinic start generated code]*/
 
+#include "pycore_modsupport.h"    // _PyArg_CheckPositional()
+
 PyDoc_STRVAR(blob_close__doc__,
 "close($self, /)\n"
 "--\n"
@@ -213,4 +215,4 @@ blob_exit(pysqlite_Blob *self, PyObject *const *args, Py_ssize_t nargs)
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=8bfd79ab12ac5385 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=27c24afc687bd772 input=a9049054013a1b77]*/

Modules/_sqlite/clinic/connection.c.h

@@ -6,6 +6,7 @@ preserve
 #  include "pycore_gc.h"          // PyGC_Head
 #  include "pycore_runtime.h"     // _Py_ID()
 #endif
+#include "pycore_modsupport.h"    // _PyArg_UnpackKeywords()
 
 static int
 pysqlite_connection_init_impl(pysqlite_Connection *self, PyObject *database,
@@ -1821,4 +1822,4 @@ exit:
 #ifndef DESERIALIZE_METHODDEF
     #define DESERIALIZE_METHODDEF
 #endif /* !defined(DESERIALIZE_METHODDEF) */
-/*[clinic end generated code: output=166bf41ad5ca1655 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=b9c27a406e329587 input=a9049054013a1b77]*/

Modules/_sqlite/clinic/cursor.c.h

@@ -6,6 +6,7 @@ preserve
 #  include "pycore_gc.h"          // PyGC_Head
 #  include "pycore_runtime.h"     // _Py_ID()
 #endif
+#include "pycore_modsupport.h"    // _PyArg_CheckPositional()
 
 static int
 pysqlite_cursor_init_impl(pysqlite_Cursor *self,
@@ -312,4 +313,4 @@ pysqlite_cursor_close(pysqlite_Cursor *self, PyObject *Py_UNUSED(ignored))
 {
     return pysqlite_cursor_close_impl(self);
 }
-/*[clinic end generated code: output=0c52a9cf54d00543 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=a8ce095c3c80cf65 input=a9049054013a1b77]*/

Modules/_sqlite/clinic/module.c.h

@@ -6,6 +6,7 @@ preserve
 #  include "pycore_gc.h"          // PyGC_Head
 #  include "pycore_runtime.h"     // _Py_ID()
 #endif
+#include "pycore_modsupport.h"    // _PyArg_UnpackKeywords()
 
 PyDoc_STRVAR(pysqlite_complete_statement__doc__,
 "complete_statement($module, /, statement)\n"
@@ -207,4 +208,4 @@ skip_optional:
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=a14893a7c2eead5e input=a9049054013a1b77]*/
+/*[clinic end generated code: output=457ab0fdbb9e1880 input=a9049054013a1b77]*/

Modules/_sqlite/clinic/row.c.h

@@ -2,6 +2,8 @@
 preserve
 [clinic start generated code]*/
 
+#include "pycore_modsupport.h"    // _PyArg_CheckPositional()
+
 static PyObject *
 pysqlite_row_new_impl(PyTypeObject *type, pysqlite_Cursor *cursor,
                       PyObject *data);
@@ -54,4 +56,4 @@ pysqlite_row_keys(pysqlite_Row *self, PyObject *Py_UNUSED(ignored))
 {
     return pysqlite_row_keys_impl(self);
 }
-/*[clinic end generated code: output=972487d535d2e7d5 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=788bf817acc02b8e input=a9049054013a1b77]*/

Modules/_sqlite/connection.c

@@ -35,6 +35,7 @@
 #include "util.h"
 
 #include "pycore_import.h"        // _PyImport_GetModuleAttrString()
+#include "pycore_modsupport.h"    // _PyArg_NoKeywords()
 #include "pycore_pyerrors.h"      // _PyErr_ChainExceptions1()
 #include "pycore_pylifecycle.h"   // _Py_IsInterpreterFinalizing()
 #include "pycore_weakref.h"       // _PyWeakref_IS_DEAD()

Modules/_sqlite/row.c

@@ -21,6 +21,10 @@
  * 3. This notice may not be removed or altered from any source distribution.
  */
 
+#ifndef Py_BUILD_CORE_BUILTIN
+#  define Py_BUILD_CORE_MODULE 1
+#endif
+
 #include "row.h"
 #include "cursor.h"