Make classes with destructor as only virtual member non-virtual

These classes are probably not meant to be used polymorphically.

taglib/mpeg/id3v2/id3v2extendedheader.h

@@ -57,7 +57,7 @@ namespace TagLib {
       /*!
        * Destroys the extended header.
        */
-      virtual ~ExtendedHeader();
+      ~ExtendedHeader();
 
       ExtendedHeader(const ExtendedHeader &) = delete;
       ExtendedHeader &operator=(const ExtendedHeader &) = delete;

taglib/mpeg/id3v2/id3v2footer.h

@@ -57,7 +57,7 @@ namespace TagLib {
       /*!
        * Destroys the footer.
        */
-      virtual ~Footer();
+      ~Footer();
 
       Footer(const Footer &) = delete;
       Footer &operator=(const Footer &) = delete;

taglib/mpeg/id3v2/id3v2header.h

@@ -63,7 +63,7 @@ namespace TagLib {
       /*!
        * Destroys the header.
        */
-      virtual ~Header();
+      ~Header();
 
       Header(const Header &) = delete;
       Header &operator=(const Header &) = delete;

taglib/mpeg/mpegheader.h

@@ -70,7 +70,7 @@ namespace TagLib {
       /*!
        * Destroys this Header instance.
        */
-      virtual ~Header();
+      ~Header();
 
       /*!
        * Returns \c true if the frame is at least an appropriate size and has

taglib/mpeg/xingheader.h

@@ -82,7 +82,7 @@ namespace TagLib {
       /*!
        * Destroy this XingHeader instance.
        */
-      virtual ~XingHeader();
+      ~XingHeader();
 
       XingHeader(const XingHeader &) = delete;
       XingHeader &operator=(const XingHeader &) = delete;