DPCLANG does not differentiate install targets from CLANG

[dvrogozh]

That's resurrection of the following issue for which I do not have permissions to reopen:

• Differentiate install targets from CLANG and ICX #21511

Configuring and building https://github.com/intel/llvm/releases/tag/v7.1.1 as follows on Ubuntu 24.04:

cmake -B _build -S llvm -G Ninja \
    -DCMAKE_BUILD_TYPE=Release \
    -DCMAKE_INSTALL_PREFIX=$(pwd)/_install \
    -DBUILD_SHARED_LIBS=ON \
    -DLLVM_BUILD_TOOLS=ON \
    -DLLVM_ENABLE_ASSERTIONS=ON \
    -DLLVM_ENABLE_DOXYGEN=OFF \
    -DLLVM_ENABLE_LLD=OFF \
    -DLLVM_ENABLE_PROJECTS='clang;sycl;llvm-spirv;opencl;xpti;xptifw;compiler-rt;libdevice;sycl-jit' \
    -DLLVM_ENABLE_RTTI=ON \
    -DLLVM_ENABLE_SPHINX=OFF \
    -DLLVM_ENABLE_ZSTD=ON \
    -DLLVM_EXTERNAL_PROJECTS='sycl;llvm-spirv;opencl;xpti;xptifw;compiler-rt;libdevice;sycl-jit' \
    -DLLVM_SPIRV_ENABLE_LIBSPIRV_DIS=OFF \
    -DLLVM_TARGETS_TO_BUILD='host;SPIRV' \
    -DSYCL_ENABLE_EXTENSION_JIT=ON \
    -DSYCL_ENABLE_MAJOR_RELEASE_PREVIEW_LIB=OFF \
    -DSYCL_ENABLE_WERROR=OFF \
    -DSYCL_ENABLE_XPTI_TRACING=ON \
    -DLLVM_EXTERNAL_LIBDEVICE_SOURCE_DIR=$(pwd)/libdevice \
    -DLLVM_EXTERNAL_LLVM_SPIRV_SOURCE_DIR=$(pwd)/llvm-spirv \
    -DLLVM_EXTERNAL_SYCL_JIT_SOURCE_DIR=$(pwd)/sycl-jit \
    -DLLVM_EXTERNAL_SYCL_SOURCE_DIR=$(pwd)/sycl \
    -DLLVM_EXTERNAL_XPTI_SOURCE_DIR=$(pwd)/xpti \
    -DLLVM_EXTERNAL_XPTIFW_SOURCE_DIR=$(pwd)/xptifw \
    -DSYCL_INCLUDE_TESTS=OFF \
    -DXPTI_ENABLE_WERROR=OFF
cmake --build _build
cmake --install _build

I am getting a number of original LLVM targets (such as clang-22) installed into the _install/bin directory which is not expected:

$ ls _install/bin/
amdgpu-arch             clang-sycl-linker  llvm-bcanalyzer          llvm-extract            llvm-opt-report   llvm-windres
analyze-build           clang-tblgen       llvm-bitcode-strip       llvm-foreach            llvm-otool        llvm-xray
append-file             cllayerinfo        llvm-cas                 llvm-gsymutil           llvm-pdbutil      nvptx-arch
bugpoint                diagtool           llvm-cat                 llvm-ifs                llvm-profdata     offload-arch
c-index-test            dpclang            llvm-cfi-verify          llvm-install-name-tool  llvm-profgen      opencl-aot
clang                   dpclang++          llvm-cgdata              llvm-ir2vec             llvm-ranlib       opt
clang++                 dpclang-cl         llvm-config              llvm-jitlink            llvm-rc           reduce-chunk-list
clang-22                dpclang-cpp        llvm-cov                 llvm-lib                llvm-readelf      sancov
clang-check             dpllvm             llvm-c-test              llvm-libtool-darwin     llvm-readobj      sanstats
clang-cl                dpsyclbin-dump     llvm-ctxprof-util        llvm-link               llvm-readtapi     scan-build
clang-cpp               dpsycl-ls          llvm-cvtres              llvm-lipo               llvm-reduce       scan-build-py
clang-extdef-mapping    dpsycl-prof        llvm-cxxdump             llvm-lto                llvm-remarkutil   scan-view
clang-format            dpsycl-sanitize    llvm-cxxfilt             llvm-lto2               llvm-rtdyld       spirv-to-ir-wrapper
clang-installapi        dpsycl-trace       llvm-cxxmap              llvm-mc                 llvm-sim          syclbin-dump
clang-linker-wrapper    dsymutil           llvm-debuginfo-analyzer  llvm-mca                llvm-size         sycl-ls
clang-nvlink-wrapper    file-table-tform   llvm-debuginfod          llvm-ml                 llvm-spirv        sycl-module-split
clang-offload-bundler   git-clang-format   llvm-debuginfod-find     llvm-ml64               llvm-split        sycl-post-link
clang-offload-deps      hmaptool           llvm-diff                llvm-modextract         llvm-stress       sycl-prof
clang-offload-extract   intercept-build    llvm-dis                 llvm-mt                 llvm-strings      sycl-sanitize
clang-offload-packager  llc                llvm-dlltool             llvm-nm                 llvm-strip        sycl-trace
clang-offload-wrapper   lli                llvm-dwarfdump           llvm-objcopy            llvm-symbolizer   verify-uselistorder
clang-refactor          llvm-addr2line     llvm-dwarfutil           llvm-objdump            llvm-tblgen
clang-repl              llvm-ar            llvm-dwp                 llvm-offload-binary     llvm-tli-checker
clang-scan-deps         llvm-as            llvm-exegesis            llvm-offload-wrapper    llvm-undname

Expectation is that dpclang compiler can be installed system-wide without overriding targets installed from other packages.

CC: @dm-vodopyanov, @sarnex, @androniychuk

[sarnex]

@dm-vodopyanov can you take a first look at this? thanks