Make RawConverter destructor virtual (fix clang++ warning).

Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>

src/rawconverter.cc

@@ -21,6 +21,10 @@
 
 using std::vector;
 
+RawConverter::~RawConverter()
+{
+}
+
 template<int BIT_DEPTH, RawFormat::Endian ENDIAN, RawFormat::Encoding ENCODING>
 class RawConverterImpl : public RawConverter
 {

src/rawconverter.hh

@@ -25,6 +25,8 @@ class RawConverter
 public:
   static RawConverter *create (const RawFormat& raw_format, Error& error);
 
+  virtual ~RawConverter() = 0;
+
   virtual void to_raw   (const std::vector<float>& samples, std::vector<unsigned char>& bytes) = 0;
   virtual void from_raw (const std::vector<unsigned char>& bytes, std::vector<float>& samples) = 0;
 };