`Clang` builds fail due to not finding `opt` when using rpath

[jfgrimm]

Ran into this when trying to build various Clang versions; results in errors like:

[ 96%] Linking LLVM bitcode libomptarget-new-nvptx-sm_86.bc
cd /dev/shm/jfg508/Clang/13.0.1/GCCcore-11.3.0-CUDA-11.7.0/llvm.obj.2/projects/openmp/libomptarget/DeviceRTL && /dev/shm/jfg508/Clang/13.0.1/GCCcore-11.3.0-CUDA-11.7.0/llvm.obj.1/bin/llvm-link -o /dev/shm/jfg508/Clang/13.0.1/GCCcore-11.3.0-CUDA-11.7.0/llvm.obj.2/projects/openmp/libomptarget/DeviceRTL/libomptarget-new-nvptx-sm_86.bc Configuration.cpp-sm_86.bc Debug.cpp-sm_86.bc Kernel.cpp-sm_86.bc Mapping.cpp-sm_86.bc Misc.cpp-sm_86.bc Parallelism.cpp-sm_86.bc Reduction.cpp-sm_86.bc State.cpp-sm_86.bc Synchronization.cpp-sm_86.bc Tasking.cpp-sm_86.bc Utils.cpp-sm_86.bc Workshare.cpp-sm_86.bc
[ 96%] Optimizing LLVM bitcode libomptarget-new-nvptx-sm_86.bc
cd /dev/shm/jfg508/Clang/13.0.1/GCCcore-11.3.0-CUDA-11.7.0/llvm.obj.2/projects/openmp/libomptarget/DeviceRTL && /tmp/eb-llp5mrdb/tmps6rxyvjf/rpath_wrappers/clang_wrapper/opt -O1 -openmp-opt-disable /dev/shm/jfg508/Clang/13.0.1/GCCcore-11.3.0-CUDA-11.7.0/llvm.obj.2/projects/openmp/libomptarget/DeviceRTL/libomptarget-new-nvptx-sm_86.bc -o /dev/shm/jfg508/Clang/13.0.1/GCCcore-11.3.0-CUDA-11.7.0/llvm.obj.2/projects/openmp/libomptarget/DeviceRTL/libomptarget-new-nvptx-sm_86.bc
/bin/sh: /tmp/eb-llp5mrdb/tmps6rxyvjf/rpath_wrappers/clang_wrapper/opt: No such file or directory