Add _PyOS_SigintEvent() include

Author: vstinner

Parser/myreadline.c

@@ -13,6 +13,7 @@
 #include "pycore_fileutils.h"     // _Py_BEGIN_SUPPRESS_IPH
 #include "pycore_interp.h"        // _PyInterpreterState_GetConfig()
 #include "pycore_pystate.h"       // _PyThreadState_GET()
+#include "pycore_signal.h"        // _PyOS_SigintEvent()
 #ifdef MS_WINDOWS
 #  ifndef WIN32_LEAN_AND_MEAN
 #    define WIN32_LEAN_AND_MEAN