rustc_driver_impl: remove some old dead logic

Author: RalfJung

Diff for: compiler/rustc_driver_impl/src/lib.rs

@@ -61,7 +61,6 @@ use rustc_session::lint::{Lint, LintId};
 use rustc_session::output::collect_crate_types;
 use rustc_session::{config, filesearch, EarlyDiagCtxt, Session};
 use rustc_span::source_map::FileLoader;
-use rustc_span::symbol::sym;
 use rustc_span::FileName;
 use rustc_target::json::ToJson;
 use rustc_target::spec::{Target, TargetTriple};
@@ -777,16 +776,8 @@ fn print_crate_info(
                     .config
                     .iter()
                     .filter_map(|&(name, value)| {
-                        // Note that crt-static is a specially recognized cfg
-                        // directive that's printed out here as part of
-                        // rust-lang/rust#37406, but in general the
-                        // `target_feature` cfg is gated under
-                        // rust-lang/rust#29717. For now this is just
-                        // specifically allowing the crt-static cfg and that's
-                        // it, this is intended to get into Cargo and then go
-                        // through to build scripts.
-                        if (name != sym::target_feature || value != Some(sym::crt_dash_static))
-                            && !sess.is_nightly_build()
+                        // On stable, exclude unstable flags.
+                        if !sess.is_nightly_build()
                             && find_gated_cfg(|cfg_sym| cfg_sym == name).is_some()
                         {
                             return None;