misc: Fix missing includes.

Change-Id: I545ff03041e8fe66dc489c6aa95c009e54df0970
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/38995
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/cpu/testers/traffic_gen/base_gen.hh

@@ -43,11 +43,14 @@
 #ifndef __CPU_TRAFFIC_GEN_BASE_GEN_HH__
 #define __CPU_TRAFFIC_GEN_BASE_GEN_HH__
 
-#include "base/bitfield.hh"
-#include "base/intmath.hh"
+#include <string>
+
+#include "base/types.hh"
 #include "mem/packet.hh"
+#include "mem/request.hh"
 
 class BaseTrafficGen;
+class SimObject;
 
 /**
  * Base class for all generators, with the shared functionality and