[llvm] [openmp] [offload][openmp] - Remove standalone build in favor of 'runtimes' (PR #170693)

[Michał Górny via llvm-commits]

mgorny wrote:

> > For `offload`, I'm getting:
> > ```
> > CMake Error at /var/tmp/portage/llvm-runtimes/offload-22.0.0.9999/work/offload/plugins-nextgen/common/CMakeLists.txt:20 (add_dependencies):
> >   The dependency target "intrinsics_gen" of target "PluginCommon" does not
> >   exist.
> > ```
> 
> Huh, I was not seeing that locally. What was your cmake command?

```
cmake -C /var/tmp/portage/llvm-runtimes/offload-22.0.0.9999/work/runtimes_build/gentoo_common_config.cmake
 -G Ninja
 -DCMAKE_INSTALL_PREFIX=/usr
 -DLLVM_ENABLE_RUNTIMES=offload
 -DOPENMP_STANDALONE_BUILD=ON
 -DOFFLOAD_LIBDIR_SUFFIX=64
 -DLLVM_ROOT=/usr/lib/llvm/22
 -DLLVM_BINARY_DIR=/usr/lib/llvm/22/bin
 -DOFFLOAD_INCLUDE_TESTS=yes
 -DLIBOMPTARGET_PLUGINS_TO_BUILD="host;cuda"
 -DLIBOMPTARGET_OMPT_SUPPORT=no
 -DBUILD_SHARED_LIBS=OFF
 -DLIBOMPTARGET_AMDGPU_ARCH=LIBOMPTARGET_AMDGPU_ARCH-NOTFOUND
 -DLIBOMPTARGET_NVPTX_ARCH=LIBOMPTARGET_NVPTX_ARCH-NOTFOUND
 -DOPENMP_LLVM_LIT_EXECUTABLE=/usr/bin/lit
 -DOPENMP_LIT_ARGS="-vv;-j;96"
 -DOPENMP_TEST_C_COMPILER=/usr/lib/ccache/bin/aarch64-unknown-
linux-gnu-clang
 -DOPENMP_TEST_CXX_COMPILER=/usr/lib/ccache/bin/aarch64-unknown-linux-gnu-clang++
 -DOPENMP_TEST_Fortran_COMPILER=
 -DCMAKE_BUILD_TYPE=RelWithDebInfo
 -DCMAKE_TOOLCHAIN_FILE=/var/tmp/portage/llvm-runtimes/offload-22.0.0.9999/work/runtimes_build/gentoo_toolchain.cmake
 /var/tmp/portage/llvm-runtimes/offload-22.0.0.9999/work/runtimes
```

(I've broken lines for readability)

https://github.com/llvm/llvm-project/pull/170693