rustdoc-json: Add tests for re-exports of primitives

Author: Enselic

src/test/rustdoc-json/primitive.rs

@@ -12,3 +12,9 @@ mod usize {}
 // @has - "$.index[*][?(@.name=='checked_add')]"
 // @!is - "$.index[*][?(@.name=='checked_add')]" $local_crate_id
 // @!has - "$.index[*][?(@.name=='is_ascii_uppercase')]"
+
+// @is - "$.index[*][?(@.kind=='import' && @.inner.name=='my_i32')].inner.id" null
+pub use i32 as my_i32;
+
+// @is - "$.index[*][?(@.kind=='import' && @.inner.name=='u32')].inner.id" null
+pub use u32;