Add @ericwf clang contracts compiler

[EricWF]

No description provided.

[mattgodbolt]

Thank you!

[mattgodbolt]

Building here: https://github.com/compiler-explorer/compiler-workflows/actions/runs/9879798035

[mattgodbolt]

Build failed:

  + export LD_LIBRARY_PATH=/opt/compiler-explorer/gcc-9.2.0/lib64
  + LD_LIBRARY_PATH=/opt/compiler-explorer/gcc-9.2.0/lib64
  + cmake -G Ninja /root/llvm-project/llvm -DLLVM_ENABLE_PROJECTS=clang '-DLLVM_ENABLE_RUNTIMES=libcxx;libcxxabilibcxx;libcxxabi;libunwind' -DCMAKE_BUILD_TYPE:STRING=Release -DCMAKE_INSTALL_PREFIX:PATH=/root/staging -DCMAKE_C_COMPILER:PATH=/opt/compiler-explorer/gcc-9.2.0/bin/gcc -DCMAKE_CXX_COMPILER:PATH=/opt/compiler-explorer/gcc-9.2.0/bin/g++ -DLLVM_BINUTILS_INCDIR:PATH=/opt/compiler-explorer/gcc-9.2.0/lib/gcc/x86_64-linux-gnu/9.2.0/plugin/include -DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD= -DLLVM_PARALLEL_LINK_JOBS=4
  -- The C compiler identification is GNU 9.2.0
  -- The CXX compiler identification is GNU 9.2.0
  -- The ASM compiler identification is GNU
  -- Found assembler: /opt/compiler-explorer/gcc-9.2.0/bin/gcc
  -- Detecting C compiler ABI info
  -- Detecting C compiler ABI info - done
  -- Check for working C compiler: /opt/compiler-explorer/gcc-9.2.0/bin/gcc - skipped
  -- Detecting C compile features
  -- Detecting C compile features - done
  -- Detecting CXX compiler ABI info
  -- Detecting CXX compiler ABI info - done
  -- Check for working CXX compiler: /opt/compiler-explorer/gcc-9.2.0/bin/g++ - skipped
  -- Detecting CXX compile features
  -- Detecting CXX compile features - done
  CMake Error at CMakeLists.txt:158 (message):
    Runtime "libcxxabilibcxx" is not a supported runtime.  Supported runtimes
    are:
    libc;libunwind;libcxxabi;pstl;libcxx;compiler-rt;openmp;llvm-libgcc;offload
  
  
  -- Configuring incomplete, errors occurred!
  Error: Process completed with exit code 1.