[clang] [llvm] [AArch64] Improve bcvtn2 and remove aarch64_neon_bfcvt intrinsics (PR #120363)

[Dmitry Vasilyev via llvm-commits]

slydiman wrote:

One more failure on Windows host using MSVC
https://lab.llvm.org/buildbot/#/builders/197/builds/919
```
FAILED: tools/clang/lib/CodeGen/CMakeFiles/obj.clangCodeGen.dir/CGBuiltin.cpp.obj 
ccache C:\PROGRA~1\MICROS~1\2022\COMMUN~1\VC\Tools\MSVC\1441~1.341\bin\Hostx64\x64\cl.exe  /nologo /TP -DCLANG_BUILD_STATIC -DGTEST_HAS_RTTI=0 -DUNICODE -D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_NONSTDC_NO_WARNINGS -D_CRT_SECURE_NO_DEPRECATE -D_CRT_SECURE_NO_WARNINGS -D_GLIBCXX_ASSERTIONS -D_HAS_EXCEPTIONS=0 -D_SCL_SECURE_NO_DEPRECATE -D_SCL_SECURE_NO_WARNINGS -D_UNICODE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -IC:\buildbot\as-builder-10\lldb-x-aarch64\build\tools\clang\lib\CodeGen -IC:\buildbot\as-builder-10\lldb-x-aarch64\llvm-project\clang\lib\CodeGen -IC:\buildbot\as-builder-10\lldb-x-aarch64\llvm-project\clang\include -IC:\buildbot\as-builder-10\lldb-x-aarch64\build\tools\clang\include -IC:\buildbot\as-builder-10\lldb-x-aarch64\build\include -IC:\buildbot\as-builder-10\lldb-x-aarch64\llvm-project\llvm\include -D__OPTIMIZE__ /Zc:inline /Zc:preprocessor /Zc:__cplusplus /Oi /bigobj /permissive- /W4 -wd4141 -wd4146 -wd4244 -wd4267 -wd4291 -wd4351 -wd4456 -wd4457 -wd4458 -wd4459 -wd4503 -wd4624 -wd4722 -wd4100 -wd4127 -wd4512 -wd4505 -wd4610 -wd4510 -wd4702 -wd4245 -wd4706 -wd4310 -wd4701 -wd4703 -wd4389 -wd4611 -wd4805 -wd4204 -wd4577 -wd4091 -wd4592 -wd4319 -wd4709 -wd5105 -wd4324 -wd4251 -wd4275 -w14062 -we4238 /Gw /O2 /Ob2  -MD  /EHs-c- /GR- -UNDEBUG -std:c++17 /showIncludes /Fotools\clang\lib\CodeGen\CMakeFiles\obj.clangCodeGen.dir\CGBuiltin.cpp.obj /Fdtools\clang\lib\CodeGen\CMakeFiles\obj.clangCodeGen.dir\ /FS -c C:\buildbot\as-builder-10\lldb-x-aarch64\llvm-project\clang\lib\CodeGen\CGBuiltin.cpp
C:\buildbot\as-builder-10\lldb-x-aarch64\llvm-project\clang\lib\CodeGen\CGBuiltin.cpp(12824): error C2039: 'iota': is not a member of 'std'
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.41.34120\include\forward_list(23): note: see declaration of 'std'
C:\buildbot\as-builder-10\lldb-x-aarch64\llvm-project\clang\lib\CodeGen\CGBuiltin.cpp(12824): error C3861: 'iota': identifier not found
C:\buildbot\as-builder-10\lldb-x-aarch64\llvm-project\clang\lib\CodeGen\CGBuiltin.cpp(12834): error C2039: 'iota': is not a member of 'std'
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.41.34120\include\forward_list(23): note: see declaration of 'std'
C:\buildbot\as-builder-10\lldb-x-aarch64\llvm-project\clang\lib\CodeGen\CGBuiltin.cpp(12834): error C3861: 'iota': identifier not found
C:\buildbot\as-builder-10\lldb-x-aarch64\llvm-project\clang\lib\CodeGen\CGBuiltin.cpp(12836): error C2039: 'iota': is not a member of 'std'
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.41.34120\include\forward_list(23): note: see declaration of 'std'
C:\buildbot\as-builder-10\lldb-x-aarch64\llvm-project\clang\lib\CodeGen\CGBuiltin.cpp(12836): error C3861: 'iota': identifier not found
```

https://github.com/llvm/llvm-project/pull/120363