[libclc] libclc: Update pow functions (PR #186890)

[via cfe-commits]

github-actions[bot] wrote:

<!--PREMERGE ADVISOR COMMENT: Linux-->
# :penguin: Linux x64 Test Results

* 1 test failed

## Failed Tests
(click on a test name to see its output)

### libclc
<details>
<summary>libclc.libclc/check-external-funcs.test</summary>

```
Exit Code: 3

Command Output (stdout):
--
ERROR: Disassembler '/home/gha/actions-runner/_work/llvm-project/llvm-project/build/./bin/llvm-dis' is not executable

--
Command Output (stderr):
--
/home/gha/actions-runner/_work/llvm-project/llvm-project/libclc/test/check_external_funcs.sh /home/gha/actions-runner/_work/llvm-project/llvm-project/build/./lib/clang/23/lib/amdgcn-amd-amdhsa-llvm/libclc.bc /home/gha/actions-runner/_work/llvm-project/llvm-project/build/./bin # RUN: at line 1
+ /home/gha/actions-runner/_work/llvm-project/llvm-project/libclc/test/check_external_funcs.sh /home/gha/actions-runner/_work/llvm-project/llvm-project/build/./lib/clang/23/lib/amdgcn-amd-amdhsa-llvm/libclc.bc /home/gha/actions-runner/_work/llvm-project/llvm-project/build/./bin

--

```
</details>

If these failures are unrelated to your changes (for example tests are broken or flaky at HEAD), please open an issue at https://github.com/llvm/llvm-project/issues and add the `infrastructure` label.

https://github.com/llvm/llvm-project/pull/186890