pub const DEFAULT_OPTION_FILE_NAMES: &[&str];Expand description
Options-file names probed in the working directory when the caller
names none, in probe order: pounce’s own name first, then upstream’s
so an ipopt.opt written for Ipopt is honored unchanged.
Upstream probes only ipopt.opt (the registered default of
option_file_name). Both are read here because a port that answers
to ipopt.opt but not to its own name is the more surprising of the
two behaviours — and gh#518 reported trying both.