Tidy up binaryBlob initialization to use SDL_zeroa()

It's simpler and more concise than writing out the SDL_memset() in full,
which means you're less likely to screw up those lines of code.

desktop_version/src/BinaryBlob.cpp

@@ -10,8 +10,8 @@
 binaryBlob::binaryBlob()
 {
 	numberofHeaders = 0;
-	SDL_memset(m_headers, 0, sizeof(m_headers));
-	SDL_memset(m_memblocks, 0, sizeof(m_memblocks));
+	SDL_zeroa(m_headers);
+	SDL_zeroa(m_memblocks);
 }
 
 #ifdef VVV_COMPILEMUSIC