[RFA v3] Return gdb::optional<std::string> from target_fileio_readlink

[Tom Tromey]

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

Tom> This is an updated version of a patch originally submitted here:
Tom> https://sourceware.org/ml/gdb-patches/2017-11/msg00556.html

Ping.

Tom