[RFA 3/3] Move logic out of symbol_find_demangled_name

[Tom Tromey]

Pedro> Before, this would set language to language_cplus, even if the
Pedro> symbol's language was Rust.
[...]
Pedro> However, this no longer forces C++, is that intended?

I think the old code was in error.

Pedro> Also, before we'd check whether gdb_demangle returned not-NULL,
Pedro> before taking the language, but now several languages
Pedro> return 1 even if gdb_demangle returns NULL:

Sorry about that.  I'll fix up the patch a bit more.

Tom