Merge from rustc

Author: RalfJung

crates/hir-def/src/attr/builtin.rs

@@ -207,7 +207,6 @@ pub const INERT_ATTRIBUTES: &[BuiltinAttribute] = &[
     ),
 
     // Entry point:
-    gated!(unix_sigpipe, Normal, template!(Word, NameValueStr: "inherit|sig_ign|sig_dfl"), ErrorFollowing, experimental!(unix_sigpipe)),
     ungated!(start, Normal, template!(Word), WarnFollowing),
     ungated!(no_start, CrateLevel, template!(Word), WarnFollowing),
     ungated!(no_main, CrateLevel, template!(Word), WarnFollowing),