RISC-V: check cfg (batch 1)

rust-lang/rust#138823 added five new extensions as compiler target features.
This commit reflects that fact and now checks static target features on
`std::arch::is_riscv_feature_detected!` as well.

*   "Zicsr"
*   "Zicntr"
*   "Zihpm"
*   "Zifencei"
*   "Zihintpause"

Author: a4lg

Diff for: crates/std_detect/src/detect/arch/riscv.rs

@@ -104,20 +104,15 @@ features! {
     /// RV128I Base Integer Instruction Set
 
     @FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] zicsr: "zicsr";
-    without cfg check: true;
     /// "Zicsr" Extension for Control and Status Register (CSR) Instructions
     @FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] zicntr: "zicntr";
-    without cfg check: true;
     /// "Zicntr" Extension for Base Counters and Timers
     @FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] zihpm: "zihpm";
-    without cfg check: true;
     /// "Zihpm" Extension for Hardware Performance Counters
 
     @FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] zifencei: "zifencei";
-    without cfg check: true;
     /// "Zifencei" Extension for Instruction-Fetch Fence
     @FEATURE: #[unstable(feature = "stdarch_riscv_feature_detection", issue = "111192")] zihintpause: "zihintpause";
-    without cfg check: true;
     /// "Zihintpause" Extension for Pause Hint
 
     @FEATURE: #[stable(feature = "riscv_ratified", since = "1.78.0")] m: "m";