patch 8.2.1783: try-catch test fails

Problem:    Try-catch test fails.
Solution:   Don't call win_enter(), only call enterering_window().
diff --git a/src/window.c b/src/window.c
index 64017bf..034a0d9 100644
--- a/src/window.c
+++ b/src/window.c
@@ -2227,7 +2227,7 @@
     }
 }
 
-    static void
+    void
 entering_window(win_T *win)
 {
     // Only matters for a prompt window.