libyang CHANGE use LY_ARRAY_SIZE_TYPE for iterator variables in LY_TREE_FOR

Because of the change in sized arrays design (780ade2101), also the
iterators and other variables used with LY_TREE_FOR or LY_TREE_SIZE
should be of LY_ARRAY_SIZE_TYPE.

Also the new LY_PRI_ARRAY_SIZE_TYPE was introduced to correctly print
the value of this type in a formatted print functions.
diff --git a/tools/lint/completion.c b/tools/lint/completion.c
index f2e8461..3a5394c 100644
--- a/tools/lint/completion.c
+++ b/tools/lint/completion.c
@@ -79,7 +79,7 @@
 static void
 get_model_completion(const char *hint, char ***matches, unsigned int *match_count)
 {
-    unsigned int u;
+    LY_ARRAY_SIZE_TYPE u;
     uint32_t idx = 0;
     const struct lys_module *module;
     void *p;