Issue #23735: Merge sighandler_t fix from 3.5
diff --git a/Modules/readline.c b/Modules/readline.c
index 9770f52..9cb1515 100644
--- a/Modules/readline.c
+++ b/Modules/readline.c
@@ -928,7 +928,7 @@
 
 #ifdef HAVE_RL_RESIZE_TERMINAL
 static volatile sig_atomic_t sigwinch_received;
-static sighandler_t sigwinch_ohandler;
+static PyOS_sighandler_t sigwinch_ohandler;
 
 static void
 readline_sigwinch_handler(int signum)