base: Add an "override" to name() in the HardBreakpoint class.

clang reports an error otherwise and fails to compile.

Change-Id: I3603d6c710641f1289e35c67f89a49f5cb71e95e
Reviewed-on: https://gem5-review.googlesource.com/7582
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

src/base/remote_gdb.cc

@@ -172,7 +172,7 @@ class HardBreakpoint : public PCEvent
         DPRINTF(GDBMisc, "creating hardware breakpoint at %#x\n", evpc);
     }
 
-    const std::string name() const { return gdb->name() + ".hwbkpt"; }
+    const std::string name() const override { return gdb->name() + ".hwbkpt"; }
 
     void
     process(ThreadContext *tc) override