Use sycl.hpp workaround only if compiler doesn't have it#439

romanovvlad merged 2 commits intointel:intelintel/llvm-test-suite:intelfrom

romanovvlad:private/vromanov/ImproveSYCL2020HeaderDetectionromanovvlad/llvm-test-suite:private/vromanov/ImproveSYCL2020HeaderDetectionCopy head branch name to clipboard