vim-patch:8.0.1564: too many #ifdefs

Problem:    Too many #ifdefs.
Solution:   Graduate the +autocmd feature. Takes away 450 #ifdefs and
            increases code size of tiny Vim by only 40 Kbyte.
f2bd8ef2b4

src/nvim/os/signal.c

@@ -157,6 +157,7 @@ static void deadly_signal(int signum)
 {
   // Set the v:dying variable.
   set_vim_var_nr(VV_DYING, 1);
+  v_dying = 1;
 
   WLOG("got signal %d (%s)", signum, signal_name(signum));