Prevent LZ encoder from hanging with known uncompressed

size. The "fix" breaks LZMA_SYNC_FLUSH at end of stream
with known uncompressed size, but since it currently seems
likely that support for encoding with known uncompressed
size will go away anyway, I'm not fixing this problem now.

src/liblzma/lz/lz_encoder.c

@@ -441,8 +441,13 @@ fill_window(lzma_coder *coder, lzma_allocator *allocator, const uint8_t *in,
 	// works correctly, because the next encoder cannot have any more
 	// output left to be produced. If it had, then our known Uncompressed
 	// Size would be invalid, which would mean that we have a bad bug.
-	if (ret == LZMA_OK && coder->lz.uncompressed_size == 0)
-		coder->lz.sequence = SEQ_FINISH;
+// 	if (ret == LZMA_OK && coder->lz.uncompressed_size == 0)
+// 		coder->lz.sequence = SEQ_FINISH;
+	// The above breaks normal encoding with known uncompressed size
+	// if input chunk size is a multiple of uncompressed size. Commenting
+	// the above out breaks LZMA_SYNC_FLUSH at end of stream whose
+	// uncompressed size is known. Support for encoding with known
+	// uncompressed may get dropped completely so I won't fix this now.
 
 	// Restart the match finder after finished LZMA_SYNC_FLUSH.
 	if (coder->lz.pending > 0