Build googletest with IntelLLVM compilers

[niranjan-nilakantan]

Describe the issue

IntelLLVM (icx/icpx) is a clang-like compiler.

It has a few differences from the normal clang compiler,
and this requires passing in additional flags during build.

e.g. for floating point handling

explicit comparison with NaN in fast floating point mode [-Wtautological-constant-compare]

Steps to reproduce the problem

Install the oneapi-basekit,
https://www.intel.com/content/www/us/en/docs/oneapi/installation-guide-linux/2023-1/apt.html#GUID-497ED29B-51A5-4402-AEA1-EA9E86DD3226

and run this.

mkdir build

cd build

cmake -DCMAKE_CXX_COMPILER=icpx -DCMAKE_C_COMPILER=icx \
    -G "Ninja Multi-Config" -DCMAKE_CONFIGURATION_TYPES="Release;RelWithDebInfo;Debug" \
    -Dgtest_build_tests=ON -Dgmock_build_tests=ON \
    ..

cmake --build . --config=Release

What version of GoogleTest are you using?

git rev-parse HEAD

cb455a71fb23303e37ce8ee5b1cde6a2c18f66a5

What operating system and version are you using?

$ lsb_release -a

No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 23.04
Release:	23.04
Codename:	lunar

What compiler and version are you using?

$ icpx -v

Intel(R) oneAPI DPC++/C++ Compiler 2023.1.0 (2023.1.0.20230320)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /opt/intel/oneapi/compiler/2023.1.0/linux/bin-llvm
Configuration file: /opt/intel/oneapi/compiler/2023.1.0/linux/bin-llvm/../bin/icpx.cfg
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/12
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/12
Candidate multilib: .;@m64
Selected multilib: .;@m64

What build system are you using?

$ cmake --version
cmake version 3.25.1

CMake suite maintained and supported by Kitware (kitware.com/cmake).

Additional context

No response