Make overriding explicit and remove redundant virtual specifiers on overriding destructors - Core & UnitTests

Source/Core/Core/Boot/DolReader.h

@@ -20,7 +20,7 @@ public:
   explicit DolReader(const std::string& filename);
   explicit DolReader(File::IOFile file);
   explicit DolReader(std::vector<u8> buffer);
-  ~DolReader();
+  ~DolReader() override;
 
   bool IsValid() const override { return m_is_valid; }
   bool IsWii() const override { return m_is_wii; }

Source/Core/Core/Boot/ElfReader.h

@@ -28,7 +28,7 @@ public:
   explicit ElfReader(const std::string& filename);
   explicit ElfReader(File::IOFile file);
   explicit ElfReader(std::vector<u8> buffer);
-  ~ElfReader();
+  ~ElfReader() override;
   u32 Read32(int off) const { return base32[off >> 2]; }
   // Quick accessors
   ElfType GetType() const { return (ElfType)(header->e_type); }