Issue an internal warning on first deprecated function call

[Andrew Cagney]

Hello,

The problem behind this was discussed in:
http://sources.redhat.com/ml/gdb/2001-03/msg00227.html

The idea is to issue an internal-warning on the first call to a 
deprecated [multi-arch] function.

The intent is to better alert the user to the possability that their GDB 
is on its last legs.

Thoughts?  Variations on the idea?
Andrew