bpo-36763: Make Py_BytesMain() public (GH-15532)

Declare Py_BytesMain() in Include/pylifecycle.h, rather in
Include/internal/pycore_pylifecycle.h.

Include/internal/pycore_pylifecycle.h

@@ -15,8 +15,6 @@ extern "C" {
  * KeyboardInterrupt exception, suggesting the user pressed ^C. */
 PyAPI_DATA(int) _Py_UnhandledKeyboardInterrupt;
 
-PyAPI_FUNC(int) Py_BytesMain(int argc, char **argv);
-
 extern int _Py_SetFileSystemEncoding(
     const char *encoding,
     const char *errors);

Include/pylifecycle.h

@@ -32,6 +32,8 @@ PyAPI_FUNC(void) _Py_NO_RETURN Py_Exit(int);
 /* Bootstrap __main__ (defined in Modules/main.c) */
 PyAPI_FUNC(int) Py_Main(int argc, wchar_t **argv);
 
+PyAPI_FUNC(int) Py_BytesMain(int argc, char **argv);
+
 /* In pathconfig.c */
 PyAPI_FUNC(void) Py_SetProgramName(const wchar_t *);
 PyAPI_FUNC(wchar_t *) Py_GetProgramName(void);