[s4u] Use forward.hpp for forward declarations

diff --git a/include/simgrid/s4u/host.hpp b/include/simgrid/s4u/host.hpp
index d9ff389..fa24695 100644 (file)
--- a/include/simgrid/s4u/host.hpp
+++ b/include/simgrid/s4u/host.hpp
@@ -16,14 +16,11 @@
 
 #include <simgrid/simix.h>
 #include <simgrid/datatypes.h>
+#include <simgrid/s4u/forward.hpp>
 
 namespace simgrid {
 namespace s4u {
 
-class Actor;
-class Storage;
-class File;
-
 /** @brief Simulated machine that can host some actors
  *
  * It represents some physical resource with computing and networking capabilities.