pub fn zerrmsg(msg: &str, errno: Option<i32>)Expand description
Port of zerrmsg(FILE *file, const char *fmt, va_list ap) from Src/utils.c:289.
C body emits the formatted message + (when locallevel > 0 or
SHINSTDIN unset) the line number prefix + “\n”. The Rust port
is invoked indirectly through zwarning — direct callers pass
pre-formatted strings.
WARNING: param names don’t match C — Rust=(msg, errno) vs C=(file, fmt, ap)
zerrmsg — see implementation.