Add mojo/c/system/{time.h,wait.h}.

mojo/public/c/system/core.h

Index: mojo/public/c/system/core.h
diff --git a/mojo/public/c/system/core.h b/mojo/public/c/system/core.h
index 6e2674f04ad3501e0e31d31023a83378572baf97..186b6da15841c36e439d69a18995b1f8ba27d17c 100644
--- a/mojo/public/c/system/core.h
+++ b/mojo/public/c/system/core.h
@@ -6,8 +6,6 @@
 //
 // TODO(vtl): Delete this header file.
 //
-// This is a catch-all header that includes everything.
-//
 // Note: This header should be compilable as C.
 
 #ifndef MOJO_PUBLIC_C_SYSTEM_CORE_H_
@@ -15,12 +13,12 @@
 
 #include "mojo/public/c/system/buffer.h"
 #include "mojo/public/c/system/data_pipe.h"
-#include "mojo/public/c/system/functions.h"
 #include "mojo/public/c/system/handle.h"
 #include "mojo/public/c/system/macros.h"
 #include "mojo/public/c/system/main.h"
 #include "mojo/public/c/system/message_pipe.h"
 #include "mojo/public/c/system/result.h"
-#include "mojo/public/c/system/types.h"
+#include "mojo/public/c/system/time.h"
+#include "mojo/public/c/system/wait.h"
 
 #endif  // MOJO_PUBLIC_C_SYSTEM_CORE_H_