vim-patch:8.0.1496: VIM_CLEAR()

Problem:    Clearing a pointer takes two lines.
Solution:   Add VIM_CLEAR() and replace vim_clear(). (Hirohito Higashi,
            closes #2629)

vim-patch:8.0.1481

src/nvim/if_cscope.c

@@ -1531,10 +1531,8 @@ static void cs_fill_results(char *tagstr, size_t totmatches, int *nummatches_a,
 
   if (totsofar == 0) {
     /* No matches, free the arrays and return NULL in "*matches_p". */
-    xfree(matches);
-    matches = NULL;
-    xfree(cntxts);
-    cntxts = NULL;
+    XFREE_CLEAR(matches);
+    XFREE_CLEAR(cntxts);
   }
   *matched = totsofar;
   *matches_p = matches;