Update XZ Utils to 5.0.3 (in deps)

src/liblzma/common/block_encoder.c

Index: src/liblzma/common/block_encoder.c
===================================================================
--- src/liblzma/common/block_encoder.c	(revision 50504)
+++ src/liblzma/common/block_encoder.c	(working copy)
@@ -144,7 +144,7 @@
 
 static lzma_ret
 block_encoder_update(lzma_coder *coder, lzma_allocator *allocator,
-		const lzma_filter *filters lzma_attribute((unused)),
+		const lzma_filter *filters lzma_attribute((__unused__)),
 		const lzma_filter *reversed_filters)
 {
 	if (coder->sequence != SEQ_CODE)
@@ -161,6 +161,11 @@
 {
 	lzma_next_coder_init(&lzma_block_encoder_init, next, allocator);
 
+	if (block == NULL)
+		return LZMA_PROG_ERROR;
+
+	// The contents of the structure may depend on the version so
+	// check the version first.
 	if (block->version != 0)
 		return LZMA_OPTIONS_ERROR;