Add commentary:Remove seek for ios::app if not.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@31059 138bc75d-0d04-0410-961f-82ee72b054a4

libio/ChangeLog

 1999-12-21  Martin v. Lwis  <loewis@informatik.hu-berlin.de>
 
 	* filebuf.cc (open): Support ios::ate if _G_HAVE_IO_FILE_OPEN.
+	Remove seek for ios::app if not.
 
 1999-12-15  Jason Merrill  <jason@casey.cygnus.com>