Introduce KMP_COMPILER_ICX macro to represent compilation with oneAPI
compiler.
Fixup flag detection and compiler ID detection in CMake. Older CMake's
detect IntelLLVM as Clang.
Fix compiler warnings.
Fixup many of the tests to have non-empty parallel regions as they are
elided by oneAPI compiler.
This change adds implementation to ompt_finalize_tool() and
ompt_get_task_memory().
Patch by Hansang Bae
Differential Revision: https://reviews.llvm.org/D61657
llvm-svn: 361309