Fix build with rustc-dep-of-std in the latest nightly

src/lib.rs

@@ -17,10 +17,7 @@
 )]
 #![cfg_attr(libc_deny_warnings, deny(warnings))]
 // Attributes needed when building as part of the standard library
-#![cfg_attr(
-    feature = "rustc-dep-of-std",
-    feature(cfg_target_vendor, link_cfg, no_core)
-)]
+#![cfg_attr(feature = "rustc-dep-of-std", feature(link_cfg, no_core))]
 #![cfg_attr(libc_thread_local, feature(thread_local))]
 // Enable extra lints:
 #![cfg_attr(feature = "extra_traits", deny(missing_debug_implementations))]