cpu: Don't forward declare RefCountingPtr

RefCountingPtr is sometimes forward declared to avoid having to
include refcnt.hh. This does not work since we typically return
instances of RefCountingPtr rather than references to instances. The
only reason this currently works is that we include refcnt.hh in
cprintf.hh, which "leaks" the header to most other source files. This
changeset replaces such forward declarations with an include of
refcnt.hh.

src/base/types.hh

@@ -42,6 +42,8 @@
 #include <cassert>
 #include <ostream>
 
+#include "base/refcnt.hh"
+
 /** uint64_t constant */
 #define ULL(N)          ((uint64_t)N##ULL)
 /** int64_t constant */
@@ -177,7 +179,6 @@ typedef int16_t PortID;
 const PortID InvalidPortID = (PortID)-1;
 
 class FaultBase;
-template <class T> class RefCountingPtr;
 typedef RefCountingPtr<FaultBase> Fault;
 
 #endif // __BASE_TYPES_HH__