Fix or hide warnings from GCC 7's -Wimplicit-fallthrough.

src/liblzma/lzma/lzma_decoder.c

@@ -16,6 +16,12 @@
 #include "lzma_decoder.h"
 #include "range_decoder.h"
 
+// The macros unroll loops with switch statements.
+// Silence warnings about missing fall-through comments.
+#if TUKLIB_GNUC_REQ(7, 0)
+#	pragma GCC diagnostic ignored "-Wimplicit-fallthrough"
+#endif
+
 
 #ifdef HAVE_SMALL
 

src/xz/list.c

@@ -484,6 +484,8 @@ parse_block_header(file_pair *pair, const lzma_index_iter *iter,
 		// If the above fails, the file is corrupt so
 		// LZMA_DATA_ERROR is a good error code.
 
+	// Fall through
+
 	case LZMA_DATA_ERROR:
 		// Free the memory allocated by lzma_block_header_decode().
 		for (size_t i = 0; filters[i].id != LZMA_VLI_UNKNOWN; ++i)