Auto merge of rust-lang#76295 - mati865:remove-mmx, r=Amanieu,oli-obk

bors · bors · commit 881e8621d609 · 2020-09-21T00:43:26.000Z
Remove MMX from Rust Follow-up to rust-lang/stdarch#890 This removes most of MMX from Rust (tests pass with small changes), keeping stable `is_x86_feature_detected!("mmx")` working.
diff --git a/core/src/lib.rs b/core/src/lib.rs
@@ -126,7 +126,6 @@
 #![feature(unwind_attributes)]
 #![feature(variant_count)]
 #![cfg_attr(bootstrap, feature(doc_alias))]
-#![feature(mmx_target_feature)]
 #![feature(tbm_target_feature)]
 #![feature(sse4a_target_feature)]
 #![feature(arm_target_feature)]
