arch-alpha: Add missing overrides

Change-Id: I3a52fcdb449c7df1612466270aa2c9b0a0f3afef
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/4281
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

src/arch/alpha/remote_gdb.hh

@@ -50,8 +50,8 @@ class RemoteGDB : public BaseRemoteGDB
 {
   protected:
     // Machine memory
-    bool acc(Addr addr, size_t len);
-    bool write(Addr addr, size_t size, const char *data);
+    bool acc(Addr addr, size_t len) override;
+    bool write(Addr addr, size_t size, const char *data) override;
 
     void insertHardBreak(Addr addr, size_t len) override;
 
@@ -75,7 +75,7 @@ class RemoteGDB : public BaseRemoteGDB
 
   public:
     RemoteGDB(System *system, ThreadContext *context);
-    BaseGdbRegCache *gdbRegs();
+    BaseGdbRegCache *gdbRegs() override;
 };
 
 } // namespace AlphaISA