GPU CMake: Bugfix: fix hardcoded old llvm version in case of manually specified clang binary

Author: davidrohr

dependencies/FindO2GPU.cmake

@@ -177,7 +177,7 @@ if(ENABLE_OPENCL2)
   endif()
   if (GPUCA_OPENCL_CLANGBIN)
     set(LLVM_CLANG ${GPUCA_OPENCL_CLANGBIN})
-    execute_process(COMMAND "which" "/usr/lib/llvm/15/bin/clang-15" OUTPUT_VARIABLE TMP_LLVM_SPIRV_PATH COMMAND_ERROR_IS_FATAL ANY)
+    execute_process(COMMAND "which" "${GPUCA_OPENCL_CLANGBIN}" OUTPUT_VARIABLE TMP_LLVM_SPIRV_PATH COMMAND_ERROR_IS_FATAL ANY)
     cmake_path(GET TMP_LLVM_SPIRV_PATH PARENT_PATH TMP_LLVM_SPIRV_PATH)
     find_program(LLVM_SPIRV llvm-spirv HINTS "${TMP_LLVM_SPIRV_PATH}")
   else()