patch 8.2.4858: K_SPECIAL may be escaped twice

Problem:    K_SPECIAL may be escaped twice.
Solution:   Avoid double escaping. (closes #10340)
diff --git a/src/proto/misc2.pro b/src/proto/misc2.pro
index e342021..fe0a4fb 100644
--- a/src/proto/misc2.pro
+++ b/src/proto/misc2.pro
@@ -24,8 +24,8 @@
 int simplify_key(int key, int *modifiers);
 int handle_x_keys(int key);
 char_u *get_special_key_name(int c, int modifiers);
-int trans_special(char_u **srcp, char_u *dst, int flags, int *did_simplify);
-int special_to_buf(int key, int modifiers, int keycode, char_u *dst);
+int trans_special(char_u **srcp, char_u *dst, int flags, int escape_ks, int *did_simplify);
+int special_to_buf(int key, int modifiers, int escape_ks, char_u *dst);
 int find_special_key(char_u **srcp, int *modp, int flags, int *did_simplify);
 int may_adjust_key_for_ctrl(int modifiers, int key);
 int may_remove_shift_modifier(int modifiers, int key);