Rollup merge of rust-lang#133238 - heiher:loong-stdarch-rexport, r=Amanieu

re-export `is_loongarch_feature_detected`

r? ``@Amanieu``

Author: jieyouxu

std/src/lib.rs

@@ -658,6 +658,8 @@ pub mod arch {
     pub use std_detect::is_aarch64_feature_detected;
     #[unstable(feature = "stdarch_arm_feature_detection", issue = "111190")]
     pub use std_detect::is_arm_feature_detected;
+    #[unstable(feature = "is_loongarch_feature_detected", issue = "117425")]
+    pub use std_detect::is_loongarch_feature_detected;
     #[unstable(feature = "is_riscv_feature_detected", issue = "111192")]
     pub use std_detect::is_riscv_feature_detected;
     #[stable(feature = "simd_x86", since = "1.27.0")]