patch 8.1.0868: crash if triggering garbage collector after a function call

Problem:    Crash if triggering garbage collector after a function call.
            (Michael Henry)
Solution:   Don't call the garbage collector right away, do it later.
            (closes #3894)

src/version.c

@@ -783,6 +783,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    868,
 /**/
     867,
 /**/