patch 8.1.2331: the option.c file is still very big

Problem:    The option.c file is still very big.
Solution:   Move a few functions to where they fit better. (Yegappan
            Lakshmanan, closes #4895)
diff --git a/src/proto/ui.pro b/src/proto/ui.pro
index 7ba82cd..e605649 100644
--- a/src/proto/ui.pro
+++ b/src/proto/ui.pro
@@ -35,6 +35,7 @@
 void clip_gen_set_selection(Clipboard_T *cbd);
 void clip_gen_request_selection(Clipboard_T *cbd);
 int clip_gen_owner_exists(Clipboard_T *cbd);
+char *check_clipboard_option(void);
 int vim_is_input_buf_full(void);
 int vim_is_input_buf_empty(void);
 int vim_free_in_input_buf(void);
@@ -43,7 +44,6 @@
 void set_input_buf(char_u *p);
 void add_to_input_buf(char_u *s, int len);
 void add_to_input_buf_csi(char_u *str, int len);
-void push_raw_key(char_u *s, int len);
 void trash_input_buf(void);
 int read_from_input_buf(char_u *buf, long maxlen);
 void fill_input_buf(int exit_on_error);