Fix warnings about missing virtual destructors

taglib/fileref.cpp

@@ -518,3 +518,11 @@ void FileRef::parse(IOStream *stream, bool readAudioProperties,
 
   d->file = detectByContent(stream, readAudioProperties, audioPropertiesStyle);
 }
+
+FileRef::FileTypeResolver::~FileTypeResolver()
+{
+}
+
+FileRef::StreamTypeResolver::~StreamTypeResolver()
+{
+}

taglib/fileref.h

@@ -91,8 +91,12 @@ namespace TagLib {
 
     class TAGLIB_EXPORT FileTypeResolver
     {
-      TAGLIB_IGNORE_MISSING_DESTRUCTOR
     public:
+      /*!
+       * Destroys this FileTypeResolver instance.
+       */
+      virtual ~FileTypeResolver() = 0;
+
       /*!
        * This method must be overridden to provide an additional file type
        * resolver.  If the resolver is able to determine the file type it should
@@ -110,8 +114,12 @@ namespace TagLib {
 
     class TAGLIB_EXPORT StreamTypeResolver : public FileTypeResolver
     {
-      TAGLIB_IGNORE_MISSING_DESTRUCTOR
     public:
+      /*!
+       * Destroys this StreamTypeResolver instance.
+       */
+      virtual ~StreamTypeResolver() = 0;
+
       virtual File *createFileFromStream(IOStream *stream,
                                bool readAudioProperties = true,
                                AudioProperties::ReadStyle

taglib/mpeg/id3v1/id3v1tag.cpp

@@ -67,6 +67,10 @@ StringHandler::StringHandler()
 {
 }
 
+StringHandler::~StringHandler()
+{
+}
+
 String ID3v1::StringHandler::parse(const ByteVector &data) const
 {
   return String(data, String::Latin1).stripWhiteSpace();

taglib/mpeg/id3v1/id3v1tag.h

@@ -59,11 +59,11 @@ namespace TagLib {
 
     class TAGLIB_EXPORT StringHandler
     {
-      TAGLIB_IGNORE_MISSING_DESTRUCTOR
     public:
-      // BIC: Add virtual destructor.
       StringHandler();
 
+      virtual ~StringHandler();
+
       /*!
        * Decode a string from \a data.  The default implementation assumes that
        * \a data is an ISO-8859-1 (Latin1) character array.

taglib/toolkit/taglib.h

@@ -32,12 +32,6 @@
 #define TAGLIB_MINOR_VERSION 0
 #define TAGLIB_PATCH_VERSION 0
 
-#if defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ > 1)) || defined(__clang__)
-#define TAGLIB_IGNORE_MISSING_DESTRUCTOR _Pragma("GCC diagnostic ignored \"-Wnon-virtual-dtor\"")
-#else
-#define TAGLIB_IGNORE_MISSING_DESTRUCTOR
-#endif
-
 #if (defined(_MSC_VER) && _MSC_VER >= 1600)
 #define TAGLIB_CONSTRUCT_BITSET(x) static_cast<unsigned long long>(x)
 #else