Rollup merge of rust-lang#116856 - oli-obk:no_effects, r=compiler-errors

Disable effects in libcore again

r? `@fee1-dead`

This was accidentally allowed by rust-lang#114776 without feature gates

Author: aliemjay

core/src/lib.rs

@@ -219,7 +219,6 @@
 #![feature(doc_cfg)]
 #![feature(doc_cfg_hide)]
 #![feature(doc_notable_trait)]
-#![feature(effects)]
 #![feature(exhaustive_patterns)]
 #![feature(extern_types)]
 #![feature(fundamental)]