patch 8.2.4223: long/int compiler warnings; function arguments swapped

Problem:    Long/int compiler warnings; function arguments swapped.
Solution:   Add type casts.  Swap arguments. (Ken Takata, closes #9632)
diff --git a/src/alloc.c b/src/alloc.c
index e3cd857..47a099f 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -705,7 +705,7 @@
 ga_init2(garray_T *gap, size_t itemsize, int growsize)
 {
     ga_init(gap);
-    gap->ga_itemsize = itemsize;
+    gap->ga_itemsize = (int)itemsize;
     gap->ga_growsize = growsize;
 }