Handle the case where the WAVE magic number was already read in a non-seekable

stream.  I don't know if the code works with non-seekable streams anyway, but
...

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%40172

src/audio/SDL_wave.c

@@ -434,7 +434,13 @@ SDL_AudioSpec * SDL_LoadWAV_RW (SDL_RWops *src, int freesrc,
 	/* Check the magic header */
 	RIFFchunk	= SDL_ReadLE32(src);
 	wavelen		= SDL_ReadLE32(src);
-	WAVEmagic	= SDL_ReadLE32(src);
+	if ( wavelen == WAVE ) { /* The RIFFchunk has already been read */
+		WAVEmagic = wavelen;
+		wavelen   = RIFFchunk;
+		RIFFchunk = RIFF;
+	} else {
+		WAVEmagic = SDL_ReadLE32(src);
+	}
 	if ( (RIFFchunk != RIFF) || (WAVEmagic != WAVE) ) {
 		SDL_SetError("Unrecognized file type (not WAVE)");
 		was_error = 1;