Bump bootstrap compiler to 1.50 beta
diff --git a/library/rtstartup/rsend.rs b/library/rtstartup/rsend.rs
index 18ee7c1..d5aca80 100644
--- a/library/rtstartup/rsend.rs
+++ b/library/rtstartup/rsend.rs
@@ -2,8 +2,7 @@
 
 #![feature(no_core)]
 #![feature(lang_items)]
-#![cfg_attr(bootstrap, feature(optin_builtin_traits))]
-#![cfg_attr(not(bootstrap), feature(auto_traits))]
+#![feature(auto_traits)]
 #![crate_type = "rlib"]
 #![no_core]