PATCH: Support the new demangler written in C++

[Gabriel Dos Reis]

Nathanael Nerode <neroden@twcny.rr.com> writes:

|  It's not acceptable for GDB to magically build 
| with the "good" demangler if there's a C++ compiler around and with 
| the "bad" demangler if there isn't; can you imagine the confusing bug 
| reports?  "It works for me with the same snapshot."  "Did you have a C++ 
| compiler in your environment?"  Ick, ick, ick, ick, ick, ick, ick.

Arguments along the same lines can be made if the demangler were
written in C. 
Which just demontrates a bad fate behind this whole bootstrapping
argument. 
Sigh.

-- Gaby