libFLAC: Fix decoder_flush with uninitialized decoder

Closes: https://sourceforge.net/p/flac/bugs/428
diff --git a/src/libFLAC/stream_decoder.c b/src/libFLAC/stream_decoder.c
index 231422c..04ce7cd 100644
--- a/src/libFLAC/stream_decoder.c
+++ b/src/libFLAC/stream_decoder.c
@@ -936,6 +936,9 @@
 	FLAC__ASSERT(0 != decoder->private_);
 	FLAC__ASSERT(0 != decoder->protected_);
 
+	if(!decoder->private_->internal_reset_hack && decoder->protected_->state == FLAC__STREAM_DECODER_UNINITIALIZED)
+		return false;
+
 	decoder->private_->samples_decoded = 0;
 	decoder->private_->do_md5_checking = false;