Rollup merge of #122896 - dpaoliello:stdarch, r=Amanieu

Update stdarch submodule

r? ```@Amanieu```

library/core/src/lib.rs

@@ -270,6 +270,7 @@
 #![feature(arm_target_feature)]
 #![feature(avx512_target_feature)]
 #![feature(hexagon_target_feature)]
+#![feature(loongarch_target_feature)]
 #![feature(mips_target_feature)]
 #![feature(powerpc_target_feature)]
 #![feature(riscv_target_feature)]