* w32reg.c (read_w32_registry_string): Fixed expanding of the environment

buffer; didn't worked at all.  Reported by Thijmen Klok.  From Werner on
stable branch.

* secmem.c (secmem_free, secmem_term): Use wipememory2() instead of
memset() to overwrite secure memory

* iobuf.c (direct_open): Handle mode 'b' if O_BINARY is available. From
Werner on stable branch.

* fileutil.c: Comment from stable branch.

util/fileutil.c

@@ -89,10 +89,10 @@ make_dirname(const char *filepath)
 
 
 
-/****************
- * Construct a filename from the NULL terminated list of parts.
- * Tilde expansion is done here.
- */
+/*
+  Construct a filename from the NULL terminated list of parts.  Tilde
+  expansion is done here.  Note that FIRST_PART must never be NULL and
+  that this function is guaranteed to return an allocated string.  */
 char *
 make_filename( const char *first_part, ... )
 {