LLVM build is completely broken if LLVM_USE_SANITIZER is set to "Undefined"

[chestnykh]

The documentation says nothing about restrictions of LLVM_USE_SANITIZER (e.g the host compiler has to be clang)
"LLVM_USE_SANITIZER:STRING
Define the sanitizer used to build LLVM binaries and tests. Possible values
are Address, Memory, MemoryWithOrigins, Undefined, Thread,
DataFlow, and Address;Undefined. Defaults to empty string."

I attach the file with all errors that i got during configure and compilation stages

llvm_errs_sanitizer_undefined_gcc.log

cmake command i use:

cmake -G "Unix Makefiles"                      \
    -DCMAKE_BUILD_TYPE=Release \
    -DCMAKE_INSTALL_PREFIX=/usr \
    -DLLVM_BINUTILS_INCDIR=/usr/include \
    -DLLVM_HOST_TRIPLE="x86_64-unknown-linux-gnu" \
    -DLLVM_USE_SANITIZER="Undefined" \
    -DLLVM_BUILD_LLVM_DYLIB=ON \
    -DLLVM_LINK_LLVM_DYLIB=ON \
    -DLLVM_INSTALL_UTILS=ON \
    -DLLVM_ENABLE_RTTI=ON \
    -DLLVM_ENABLE_FFI=ON \
    -DLLVM_ENABLE_PROJECTS="clang;compiler-rt;lld;bolt" \
    -DCLANG_LINK_CLANG_DYLIB=ON \
    -DLLDB_USE_SYSTEM_SIX=1 \
    -DLIBOMP_INSTALL_ALIASES=OFF \
    -DLLVM_TARGETS_TO_BUILD="X86;ARM" \
    -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi;libunwind" \
    -DPOLLY_ENABLE_GPGPU_CODEGEN=ON \
    ../llvm

[vitalybuka]

compiler-rt should go into LLVM_ENABLE_RUNTIMES,
using it from LLVM_ENABLE_PROJECTS is deprecated and probably unsupported.