[clang] [Win/X86] Make _m_prefetch[w] builtins to avoid winnt.h conflicts (PR #115099)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `lldb-aarch64-ubuntu` running on `linaro-lldb-aarch64-ubuntu` while building `clang` at step 4 "build".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/59/builds/12182

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 4 (build) failure: build (failure)
...
156.591 [2934/3/3531] Building AttrHasAttributeImpl.inc...
156.597 [2934/2/3532] Building BuiltinsNVPTX.inc...
156.603 [2934/1/3533] Building BuiltinsHexagon.inc...
156.609 [2924/10/3534] Building BuiltinsRISCV.inc...
156.609 [2923/10/3535] Building BuiltinsSPIRV.inc...
156.609 [2922/10/3536] Building BuiltinsX86_64.inc...
156.610 [2921/10/3537] Building arm_fp16.inc...
156.626 [2920/10/3538] Building arm_neon.inc...
156.626 [2920/9/3539] Building arm_immcheck_types.inc...
156.626 [2920/8/3540] Building BuiltinsX86.inc...
FAILED: tools/clang/include/clang/Basic/BuiltinsX86.inc /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/tools/clang/include/clang/Basic/BuiltinsX86.inc 
cd /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build && /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/bin/clang-tblgen -gen-clang-builtins -I /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/llvm-project/clang/include/clang/Basic -I/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/llvm-project/clang/include -I/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/tools/clang/include -I/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/include -I/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/llvm-project/llvm/include /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/llvm-project/clang/include/clang/Basic/BuiltinsX86.td --write-if-changed -o tools/clang/include/clang/Basic/BuiltinsX86.inc -d tools/clang/include/clang/Basic/BuiltinsX86.inc.d
/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/llvm-project/clang/include/clang/Basic/BuiltinsX86.td:147:7: error: Unexpected header name
  def _m_prefetch : X86LibBuiltin<"void(void *)">;
      ^
156.628 [2920/7/3541] Building arm_mve_builtins.inc...
156.631 [2920/6/3542] Building arm_mve_builtin_sema.inc...
156.633 [2920/5/3543] Building arm_mve_builtin_aliases.inc...
156.640 [2920/4/3544] Building arm_sve_typeflags.inc...
156.646 [2920/3/3545] Building arm_mve_builtin_cg.inc...
156.712 [2920/2/3546] Building arm_sve_builtins.inc...
156.716 [2920/1/3547] Building arm_sve_builtin_cg.inc...
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/115099