[clang] [llvm] [RISCV] Remove experimental from Zacas. (PR #83195)

[Fangrui Song via cfe-commits]

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@@ -103,6 +103,7 @@ Changes to the RISC-V Backend
 * Codegen support was added for the Zimop (May-Be-Operations) extension.
 * The experimental Ssnpm, Smnpm, Smmpm, Sspm, and Supm 0.8.1 Pointer Masking extensions are supported.
 * The experimental Ssqosid extension is supported.
+* Zacas is is no longer experimental.
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MaskRay wrote:

typo: `is`

https://github.com/llvm/llvm-project/pull/83195