Remove the virtual specifier for functions with the override specifier

`override` guarantees that the function is virtual (in addition
to that the function is overriding a virtual function from a base
class).

src/dbwrapper.cpp

@@ -19,7 +19,7 @@ class CBitcoinLevelDBLogger : public leveldb::Logger {
 public:
     // This code is adapted from posix_logger.h, which is why it is using vsprintf.
     // Please do not do this in normal code
-    virtual void Logv(const char * format, va_list ap) override {
+    void Logv(const char * format, va_list ap) override {
             if (!LogAcceptCategory(BCLog::LEVELDB)) {
                 return;
             }

src/keystore.h

@@ -97,14 +97,14 @@ public:
         }
         return false;
     }
-    virtual bool AddCScript(const CScript& redeemScript) override;
-    virtual bool HaveCScript(const CScriptID &hash) const override;
-    virtual bool GetCScript(const CScriptID &hash, CScript& redeemScriptOut) const override;
+    bool AddCScript(const CScript& redeemScript) override;
+    bool HaveCScript(const CScriptID &hash) const override;
+    bool GetCScript(const CScriptID &hash, CScript& redeemScriptOut) const override;
 
-    virtual bool AddWatchOnly(const CScript &dest) override;
-    virtual bool RemoveWatchOnly(const CScript &dest) override;
-    virtual bool HaveWatchOnly(const CScript &dest) const override;
-    virtual bool HaveWatchOnly() const override;
+    bool AddWatchOnly(const CScript &dest) override;
+    bool RemoveWatchOnly(const CScript &dest) override;
+    bool HaveWatchOnly(const CScript &dest) const override;
+    bool HaveWatchOnly() const override;
 };
 
 typedef std::vector<unsigned char, secure_allocator<unsigned char> > CKeyingMaterial;