vim-patch:8.1.0360: using an external diff program is slow and inflexible

Problem:    Using an external diff program is slow and inflexible.
Solution:   Include the xdiff library. (Christian Brabandt)
            Use it by default.

e828b7621c

vim-patch:8.1.0360
vim-patch:8.1.0364
vim-patch:8.1.0366
vim-patch:8.1.0370
vim-patch:8.1.0377
vim-patch:8.1.0378
vim-patch:8.1.0381
vim-patch:8.1.0396
vim-patch:8.1.0432

src/nvim/globals.h

@@ -1125,8 +1125,7 @@ EXTERN FILE *time_fd INIT(= NULL);  /* where to write startup timing */
  * can't do anything useful with the value.  Assign to this variable to avoid
  * the warning.
  */
-EXTERN int ignored;
-EXTERN char *ignoredp;
+EXTERN int vim_ignored;
 
 // Start a msgpack-rpc channel over stdin/stdout.
 EXTERN bool embedded_mode INIT(= false);