Eliminate CopySamples calls where destination is always float...

.. Call the function SamplesToFloats instead, or in one place, where source
is also always float, just do memcpy.

Dithering never happened in these cases.

src/SqliteSampleBlock.cpp

@@ -806,11 +806,8 @@ void SqliteSampleBlock::CalcSummary(Sizes sizes)
    else
    {
       samplebuffer.reinit((unsigned) mSampleCount);
-      CopySamples(mSamples.get(),
-                  mSampleFormat,
-                  (samplePtr) samplebuffer.get(),
-                  floatSample,
-                  mSampleCount);
+      SamplesToFloats(mSamples.get(), mSampleFormat,
+         samplebuffer.get(), mSampleCount);
       samples = samplebuffer.get();
    }