updated headers in gz* files

zlibWrapper/gzlib.c

@@ -1,3 +1,6 @@
+/* gzlib.c contains minimal changes required to be compiled with zlibWrapper:
+ * - gz_statep was converted to union to work with -Wstrict-aliasing=1      */
+
 /* gzlib.c -- zlib functions common to reading and writing gzip files
  * Copyright (C) 2004, 2010, 2011, 2012, 2013 Mark Adler
  * For conditions of distribution and use, see copyright notice in zlib.h