[PATCH]Add gnat demangler

[Richard Kenner]

    The following code is taken from H.J. Lu's version of binutils. It
    implements a demangler for the GNAT Ada compiler. The author of this
    code is unknown. I've asked Doug Rupp of GNAT if he knew who wrote the
    code and he said it looked familar, but did not know. 

It's in a file in the ACT source tree, so that's undoubtable why it
looked familiar to him.

    Can this code be added without knowing the author?

No.  I'm trying to find out who wrote it.