adds missing namespaces

src/sysc/core_complex.h

@@ -165,8 +165,8 @@ public:
             quantum_keeper.reset();
         }
         last_sync_cycle = cycle;
-        ibus_inc = SC_ZERO_TIME;
-        dbus_inc = SC_ZERO_TIME;
+        ibus_inc = sc_core::SC_ZERO_TIME;
+        dbus_inc = sc_core::SC_ZERO_TIME;
     }
 
     bool read_mem(uint64_t addr, unsigned length, uint8_t *const data, bool is_fetch);