[clang] [llvm] [RISCV] Allow `Zicsr`/`Zifencei` to duplicate with `g` (PR #136842)

[Luke Lau via cfe-commits]

================
@@ -717,6 +716,15 @@ RISCVISAInfo::parseArchString(StringRef Arch, bool EnableExperimentalExtension,
     } while (!Ext.empty());
   }
 
+  // We add Zicsr/Zifenci as final to allow duplicated "zicsr"/"zifencei".
----------------
lukel97 wrote:

Nit, give an example that it's duplicated with g?

```suggestion
  // We add Zicsr/Zifenci as final to allow duplicated "rv64g_zicsr_zifencei".
```

https://github.com/llvm/llvm-project/pull/136842