refactor: Add a few missing overrides

make ~XThreadExit() override
 make ~ArchString() overide
 make ~ArchNetworkBDS() overide

src/lib/arch/ArchString.h

@@ -24,7 +24,7 @@ public:
   ArchString() = default;
   ArchString(const ArchString &) = delete;
   ArchString(ArchString &&) = delete;
-  ~ArchString() = default;
+  ~ArchString() override = default;
 
   ArchString &operator=(const ArchString &) = delete;
   ArchString &operator=(ArchString &&) = delete;

src/lib/arch/unix/ArchNetworkBSD.h

@@ -63,7 +63,7 @@ public:
   }
   ArchNetworkBSD(ArchNetworkBSD const &) = delete;
   ArchNetworkBSD(ArchNetworkBSD &&) = delete;
-  ~ArchNetworkBSD() = default;
+  ~ArchNetworkBSD() override = default;
 
   ArchNetworkBSD &operator=(ArchNetworkBSD const &) = delete;
   ArchNetworkBSD &operator=(ArchNetworkBSD &&) = delete;

src/lib/mt/XThread.h

@@ -23,7 +23,7 @@ public:
   {
     // do nothing
   }
-  ~XThreadExit() = default;
+  ~XThreadExit() override = default;
 
 public:
   void *m_result;