library: update stdarch submodule

add feature target_feature_11 and riscv_target_feature

library/core/src/lib.rs

@@ -210,6 +210,7 @@
 #![feature(simd_ffi)]
 #![feature(staged_api)]
 #![feature(stmt_expr_attributes)]
+#![feature(target_feature_11)]
 #![feature(trait_alias)]
 #![feature(transparent_unions)]
 #![feature(try_blocks)]
@@ -225,6 +226,7 @@
 #![feature(hexagon_target_feature)]
 #![feature(mips_target_feature)]
 #![feature(powerpc_target_feature)]
+#![feature(riscv_target_feature)]
 #![feature(rtm_target_feature)]
 #![feature(sse4a_target_feature)]
 #![feature(tbm_target_feature)]