[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 `llvm-x86_64-debian-dylib` running on `gribozavr4` while building `clang` at step 5 "build-unified-tree".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/60/builds/18711

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

```
Step 5 (build-unified-tree) failure: build (failure)
...
0.260 [6596/96/444] Building AttrImpl.inc...
0.260 [6595/96/445] Building AttrList.inc...
0.261 [6594/96/446] Building riscv_sifive_vector_builtin_cg.inc...
0.261 [6594/95/447] Building riscv_sifive_vector_builtin_sema.inc...
0.261 [6594/94/448] Building AttrParsedAttrList.inc...
0.261 [6594/93/449] Building RegularKeywordAttrInfo.inc...
0.261 [6594/92/450] Building AttrHasAttributeImpl.inc...
0.261 [6594/91/451] Building CXX11AttributeInfo.inc...
0.262 [6594/90/452] Building BuiltinsHexagon.inc...
0.262 [6594/89/453] Building BuiltinsX86.inc...
FAILED: tools/clang/include/clang/Basic/BuiltinsX86.inc /b/1/llvm-x86_64-debian-dylib/build/tools/clang/include/clang/Basic/BuiltinsX86.inc 
cd /b/1/llvm-x86_64-debian-dylib/build && /b/1/llvm-x86_64-debian-dylib/build/bin/clang-tblgen -gen-clang-builtins -I /b/1/llvm-x86_64-debian-dylib/llvm-project/clang/include/clang/Basic -I/b/1/llvm-x86_64-debian-dylib/llvm-project/clang/include -I/b/1/llvm-x86_64-debian-dylib/build/tools/clang/include -I/b/1/llvm-x86_64-debian-dylib/build/include -I/b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/include /b/1/llvm-x86_64-debian-dylib/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
/b/1/llvm-x86_64-debian-dylib/llvm-project/clang/include/clang/Basic/BuiltinsX86.td:147:7: error: Unexpected header name
  def _m_prefetch : X86LibBuiltin<"void(void *)">;
      ^
0.262 [6594/88/454] Building arm_sme_streaming_attrs.inc...
0.262 [6594/87/455] Building arm_sme_builtins_za_state.inc...
0.262 [6594/86/456] Building Nodes.inc...
0.262 [6594/85/457] Building NodeClasses.inc...
0.263 [6594/84/458] Building arm_bf16.h...
0.263 [6594/83/459] Building Checkers.inc...
0.263 [6594/82/460] Building arm_fp16.h...
0.265 [6594/81/461] Building arm_immcheck_types.inc...
0.266 [6594/80/462] Building arm_sve_typeflags.inc...
0.267 [6594/79/463] Building arm_cde.h...
0.269 [6594/78/464] Building AttrSubMatchRulesParserStringSwitches.inc...
0.269 [6594/77/465] Building arm_sme_builtins.inc...
0.270 [6594/76/466] Building arm_sme_builtin_cg.inc...
0.270 [6594/75/467] Building arm_sme_sema_rangechecks.inc...
0.271 [6594/74/468] Building arm_sme.h...
0.272 [6594/73/469] Building arm_vector_types.h...
0.274 [6594/72/470] Building AttrParserStringSwitches.inc...
0.274 [6594/71/471] Building AttrTemplateInstantiate.inc...
0.275 [6594/70/472] Building AttrSpellingListIndex.inc...
0.276 [6594/69/473] Building AttrPCHRead.inc...
0.276 [6594/68/474] Building AttrPCHWrite.inc...
0.277 [6594/67/475] Building AttrParsedAttrKinds.inc...
0.278 [6594/66/476] Building arm_mve_builtin_aliases.inc...
0.278 [6594/65/477] Building arm_neon.inc...
0.283 [6594/64/478] Building arm_mve_builtin_sema.inc...
0.295 [6594/63/479] Building riscv_vector.h...
0.297 [6594/62/480] Building DiagnosticSerializationKinds.inc...
0.298 [6594/61/481] Building AttrParsedAttrImpl.inc...
0.300 [6594/60/482] Building DiagnosticFrontendKinds.inc...
0.302 [6594/59/483] Building arm_sve_streaming_attrs.inc...
0.303 [6594/58/484] Building DiagnosticDriverEnums.inc...
0.303 [6594/57/485] Building DiagnosticASTEnums.inc...
0.304 [6594/56/486] Building arm_mve_builtins.inc...
0.306 [6594/55/487] Building DiagnosticLexEnums.inc...

```

</details>

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