* fhandler_disk_file.cc (fhandler_disk_file::link): Revert to checking

for binary in case of .exe files.
	* ntdll.h (RtlPrefixUnicodeString): Declare.
	* path.cc (path_conv::is_binary): New method.
	* path.h (path_conv::is_binary): Declare.
	* syscalls.cc (rename_append_suffix): New static helper function for
	rename.
	(rename): Rewrite.  New suffix tests.  Use native NT functions.

winsup/cygwin/path.h

@@ -300,6 +300,7 @@ class path_conv
   {
     return (sizeof (*this) - sizeof (path)) + strlen (path) + 1 + normalized_path_size;
   }
+  bool is_binary ();
 
   unsigned __stdcall ndisk_links (DWORD);
   char *normalized_path;