patch 9.0.0749: alloc/free of buffer for each quickfix entry is inefficient

Problem:    Alloc/free of buffer for each quickfix entry is inefficient.
Solution:   Use a shared grow array. (Yegappan Lakshmanan, closes #11365)
diff --git a/src/alloc.c b/src/alloc.c
index 1032462..583ea87 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -472,15 +472,7 @@
 # endif
 
 # ifdef FEAT_QUICKFIX
-    {
-	win_T	    *win;
-	tabpage_T   *tab;
-
-	qf_free_all(NULL);
-	// Free all location lists
-	FOR_ALL_TAB_WINDOWS(tab, win)
-	    qf_free_all(win);
-    }
+    free_quickfix();
 # endif
 
     // Close all script inputs.