Eval: do not join a list if it's empty anyway #2441

This spares some work and also prevents list_join() from calling ga_init()
with a growsize of 0 which would lead to the nvimlog being littered with:

  [warning @ ga_set_growsize:64] 17675 - trying to set an invalid ga_growsize: 0

Also in Vim 7.4.702
  5216f767d4

src/nvim/eval.c

@@ -5418,6 +5418,10 @@ list_join_inner (
  */
 static int list_join(garray_T *gap, list_T *l, char_u *sep, int echo_style, int copyID)
 {
+  if (l->lv_len < 1) {
+    return OK;
+  }
+
   garray_T join_ga;
   int retval;
 

src/nvim/version.c

@@ -67,6 +67,35 @@ static char *features[] = {
 
 // clang-format off
 static int included_patches[] = {
+  702,
+  //701,
+  //700,
+  //699,
+  //698,
+  //697,
+  //696,
+  //695,
+  //694,
+  //693,
+  //692,
+  //691,
+  //690,
+  //689,
+  //688,
+  //687,
+  //686,
+  //685,
+  //684,
+  //683,
+  //682,
+  //681,
+  //680,
+  //679,
+  //678,
+  //677,
+  //676,
+  //675,
+  //674,
   673,
   //672,
   //671,