[llvm] Support to export dll on windows

[FrankXie05]

Fix #26325

Note: Port llvm supports export DLL on Windows by passing option LLVM_EXPORT_SYMBOLS_FOR_PLUGINS, and supports Plugins correctly.

[github-actions]

You have modified or added at least one portfile where deprecated functions are used.

If you feel able to do so, please consider migrating them to the new functions:
vcpkg_install_cmake -> vcpkg_cmake_install (from port vcpkg-cmake)
vcpkg_build_cmake -> vcpkg_cmake_build (from port vcpkg-cmake)
vcpkg_configure_cmake -> vcpkg_cmake_configure (Please remove the option PREFER_NINJA) (from port vcpkg-cmake)
vcpkg_fixup_cmake_targets -> vcpkg_cmake_config_fixup (from port vcpkg-cmake-config)
vcpkg_extract_source_archive_ex -> vcpkg_extract_source_archive
vcpkg_build_msbuild -> vcpkg_install_msbuild
vcpkg_copy_tool_dependencies -> vcpkg_copy_tools
vcpkg_apply_patches should be replaced by the PATCHES arguments to the "extract" helpers (e.g. vcpkg_from_github())

In the ports that use the new function, you have to add the corresponding dependencies:

{
  "name": "vcpkg-cmake",
  "host": true
},
{
  "name": "vcpkg-cmake-config",
  "host": true
}

The following files are affected:

• ports/llvm/portfile.cmake

[github-actions]

You have modified or added at least one portfile where deprecated functions are used.

If you feel able to do so, please consider migrating them to the new functions:
vcpkg_install_cmake -> vcpkg_cmake_install (from port vcpkg-cmake)
vcpkg_build_cmake -> vcpkg_cmake_build (from port vcpkg-cmake)
vcpkg_configure_cmake -> vcpkg_cmake_configure (Please remove the option PREFER_NINJA) (from port vcpkg-cmake)
vcpkg_fixup_cmake_targets -> vcpkg_cmake_config_fixup (from port vcpkg-cmake-config)
vcpkg_extract_source_archive_ex -> vcpkg_extract_source_archive
vcpkg_build_msbuild -> vcpkg_install_msbuild
vcpkg_copy_tool_dependencies -> vcpkg_copy_tools
vcpkg_apply_patches should be replaced by the PATCHES arguments to the "extract" helpers (e.g. vcpkg_from_github())

In the ports that use the new function, you have to add the corresponding dependencies:

{
  "name": "vcpkg-cmake",
  "host": true
},
{
  "name": "vcpkg-cmake-config",
  "host": true
}

The following files are affected:

• ports/llvm/portfile.cmake

[github-actions]

You have modified or added at least one portfile where deprecated functions are used.

If you feel able to do so, please consider migrating them to the new functions:
vcpkg_install_cmake -> vcpkg_cmake_install (from port vcpkg-cmake)
vcpkg_build_cmake -> vcpkg_cmake_build (from port vcpkg-cmake)
vcpkg_configure_cmake -> vcpkg_cmake_configure (Please remove the option PREFER_NINJA) (from port vcpkg-cmake)
vcpkg_fixup_cmake_targets -> vcpkg_cmake_config_fixup (from port vcpkg-cmake-config)
vcpkg_extract_source_archive_ex -> vcpkg_extract_source_archive
vcpkg_build_msbuild -> vcpkg_install_msbuild
vcpkg_copy_tool_dependencies -> vcpkg_copy_tools
vcpkg_apply_patches should be replaced by the PATCHES arguments to the "extract" helpers (e.g. vcpkg_from_github())

In the ports that use the new function, you have to add the corresponding dependencies:

{
  "name": "vcpkg-cmake",
  "host": true
},
{
  "name": "vcpkg-cmake-config",
  "host": true
}

The following files are affected:

• ports/llvm/portfile.cmake

[github-actions]

You have modified or added at least one portfile where deprecated functions are used.

If you feel able to do so, please consider migrating them to the new functions:
vcpkg_install_cmake -> vcpkg_cmake_install (from port vcpkg-cmake)
vcpkg_build_cmake -> vcpkg_cmake_build (from port vcpkg-cmake)
vcpkg_configure_cmake -> vcpkg_cmake_configure (Please remove the option PREFER_NINJA) (from port vcpkg-cmake)
vcpkg_fixup_cmake_targets -> vcpkg_cmake_config_fixup (from port vcpkg-cmake-config)
vcpkg_extract_source_archive_ex -> vcpkg_extract_source_archive
vcpkg_build_msbuild -> vcpkg_install_msbuild
vcpkg_copy_tool_dependencies -> vcpkg_copy_tools
vcpkg_apply_patches should be replaced by the PATCHES arguments to the "extract" helpers (e.g. vcpkg_from_github())

In the ports that use the new function, you have to add the corresponding dependencies:

{
  "name": "vcpkg-cmake",
  "host": true
},
{
  "name": "vcpkg-cmake-config",
  "host": true
}

The following files are affected:

• ports/llvm/portfile.cmake

[github-actions]

You have modified or added at least one portfile where deprecated functions are used.

If you feel able to do so, please consider migrating them to the new functions:
vcpkg_install_cmake -> vcpkg_cmake_install (from port vcpkg-cmake)
vcpkg_build_cmake -> vcpkg_cmake_build (from port vcpkg-cmake)
vcpkg_configure_cmake -> vcpkg_cmake_configure (Please remove the option PREFER_NINJA) (from port vcpkg-cmake)
vcpkg_fixup_cmake_targets -> vcpkg_cmake_config_fixup (from port vcpkg-cmake-config)
vcpkg_extract_source_archive_ex -> vcpkg_extract_source_archive
vcpkg_build_msbuild -> vcpkg_install_msbuild
vcpkg_copy_tool_dependencies -> vcpkg_copy_tools
vcpkg_apply_patches should be replaced by the PATCHES arguments to the "extract" helpers (e.g. vcpkg_from_github())

In the ports that use the new function, you have to add the corresponding dependencies:

{
  "name": "vcpkg-cmake",
  "host": true
},
{
  "name": "vcpkg-cmake-config",
  "host": true
}

The following files are affected:

• ports/llvm/portfile.cmake

[MonicaLiu0311]

Closing this PR since it seems that no progress is being made. Please ping us to reopen if work is still being done.

[FrankXie05]

This PR #23734 has installed the dll LLVM-C.dll.