[FYI] Handle TYPE_CODE_PTR when printing Rust types

[Tom Tromey]

>>>>> "Tom" == Tom Tromey <tom@tromey.com> writes:

Tom> gdb/ChangeLog
Tom> 2018-11-16  Tom Tromey  <tom@tromey.com>
Tom> 	PR rust/23625:
Tom> 	* rust-lang.c (rust_internal_print_type): Handle TYPE_CODE_PTR.

I sent this too soon -- it's not actually ready.
I'll resend next week.

Tom