patch 9.0.0912: libvterm with modifyOtherKeys level 2 does not match xterm

Problem:    libvterm with modifyOtherKeys level 2 does not match xterm.
Solution:   Adjust key code escape sequences to be the same as what xterm
            sends in modifyOtherKeys level 2 mode.  Check the value of
            no_reduce_keys before using it.
diff --git a/src/proto/terminal.pro b/src/proto/terminal.pro
index 7a7c507..f7ba72b 100644
--- a/src/proto/terminal.pro
+++ b/src/proto/terminal.pro
@@ -15,6 +15,7 @@
 int term_check_timers(int next_due_arg, proftime_T *now);
 int term_in_normal_mode(void);
 void term_enter_job_mode(void);
+void check_no_reduce_keys(void);
 int send_keys_to_term(term_T *term, int c, int modmask, int typed);
 int terminal_is_active(void);
 cursorentry_T *term_get_cursor_shape(guicolor_T *fg, guicolor_T *bg);