[runtimes] - Use cmake semicolon generator expression for rocr-runtime (llvm#3212)

Cmake consumes the semicolon and leaves a space between the paths. We
need the semicolon to stay so CMAKE_PREFIX_PATH can be properly
assembled and used.

Author: estewart08

llvm/runtimes/CMakeLists.txt

@@ -523,7 +523,7 @@ if(build_runtimes)
     # With ROCm 6.3 the ROCr runtime and the thunk layer share a single repository.
     # No need to provide a separate path for ROCt.
     if (OFFLOAD_EXTERNAL_PROJECT_UNIFIED_ROCR OR DEFINED LIBOMPTARGET_EXTERNAL_PROJECT_ROCM_DEVICE_LIBS_PATH)
-      list(APPEND extra_cmake_args "-DCMAKE_PREFIX_PATH=${CMAKE_BINARY_DIR}/lib/cmake;${CMAKE_PREFIX_PATH}")
+      list(APPEND extra_cmake_args "-DCMAKE_PREFIX_PATH=${CMAKE_BINARY_DIR}/lib/cmake$<SEMICOLON>${CMAKE_PREFIX_PATH}")
     endif()
     if (OFFLOAD_EXTERNAL_PROJECT_UNIFIED_ROCR)
       if(NOT DEFINED LIBOMPTARGET_EXTERNAL_PROJECT_HSA_PATH)