iwyu: minor changes

test/lib/emitter/plugin/main.cpp

@@ -1,5 +1,6 @@
 #define CR_HOST
 
+#include <functional>
 #include <gtest/gtest.h>
 #include <common/boxed_type.h>
 #include <common/emitter.h>

test/lib/emitter/shared/main.cpp

@@ -1,3 +1,4 @@
+#include <functional>
 #include <gtest/gtest.h>
 #include <common/boxed_type.h>
 #include <common/emitter.h>

test/lib/registry/plugin/main.cpp

@@ -6,6 +6,7 @@
 #include <cr.h>
 #include <entt/entity/entity.hpp>
 #include <entt/entity/registry.hpp>
+#include <entt/entity/view.hpp>
 
 TEST(Lib, Registry) {
     constexpr auto count = 3;

test/lib/registry/shared/main.cpp

@@ -4,6 +4,7 @@
 #include <entt/core/attribute.h>
 #include <entt/entity/entity.hpp>
 #include <entt/entity/registry.hpp>
+#include <entt/entity/view.hpp>
 
 ENTT_API void update(entt::registry &, int);
 ENTT_API void insert(entt::registry &);