patch 8.1.2350: other text for CTRL-V in Insert mode with modifyOtherKeys

Problem:    Other text for CTRL-V in Insert mode with modifyOtherKeys.
Solution:   Convert the Escape sequence back to key as if modifyOtherKeys is
            not set, and use CTRL-SHIFT-V to get the Escape sequence itself.
            (closes #5254)

src/term.c

@@ -4277,7 +4277,7 @@ put_string_in_typebuf(
 /*
  * Decode a modifier number as xterm provides it into MOD_MASK bits.
  */
-    static int
+    int
 decode_modifiers(int n)
 {
     int	    code = n - 1;