Update zlib to 1.2.12

libs/zlib-1.2.12/infback.c

@@ -1,5 +1,5 @@
 /* infback.c -- inflate using a call-back interface
- * Copyright (C) 1995-2016 Mark Adler
+ * Copyright (C) 1995-2022 Mark Adler
  * For conditions of distribution and use, see copyright notice in zlib.h
  */
 
@@ -477,6 +477,7 @@ void FAR *out_desc;
             }
             Tracev((stderr, "inflate:       codes ok\n"));
             state->mode = LEN;
+                /* fallthrough */
 
         case LEN:
             /* use inflate_fast() if we have enough input and output */