message: ISPC v1.13 is potentially problematic
diff: ## SPDX-License-Identifier: Apache-2.0
  # ISPC versions to look for, in decending order (newest first)
  -set(ISPC_VERSION_WORKING "1.13.0" "1.12.0" "1.10.0")
  +set(ISPC_VERSION_WORKING "1.12.0" "1.10.0")
  list(GET ISPC_VERSION_WORKING -1 ISPC_VERSION_REQUIRED)
  if (NOT ISPC_EXECUTABLE)
  @@ -61,6 +61,11 @@ endif()
  if ("${ISPC_VERSION}" STREQUAL "1.11.0")
  message(FATAL_ERROR "ISPC v1.11.0 is incompatible with OSPRay.")
  endif()
  +message(STATUS "Found ISPC v${ISPC_VERSION}: ${ISPC_EXECUTABLE}")
  +list(FIND ISPC_VERSION_WORKING ${ISPC_VERSION} ISPC_VERSION_TESTED)
  +if (ISPC_VERSION_TESTED EQUAL -1)
  + message(WARNING "Using untested version ${ISPC_VERSION} of Intel SPMD Compiler (ISPC), proceed at own risk. Supported versions are ${ISPC_VERSION_WORKING}.")
  +endif()
  set(OSPRAY_ISPC_ADDRESSING 32 CACHE STRING "32 vs 64 bit addressing in ispc")
  set_property(CACHE OSPRAY_ISPC_ADDRESSING PROPERTY STRINGS 32 64)
  