Add test for general bf16 isnan impl

[jinge90]

Re-submit #1509 . Previously, this patch led to CUDA backend pre-commit failure, the root cause is a typo in patch, the new PR has fixed the typo and tested on CUDA backend.

[jinge90]

Hi, @bader and @aelovikov-intel
I found the root cause of intel/llvm#8040 and fixed it this PR.
Thanks very much.

[aelovikov-intel]

I found the root cause of intel/llvm#8040 and fixed it this PR

What was it?

[jinge90]

I found the root cause of intel/llvm#8040 and fixed it this PR

What was it?

The error code is set when function "check" returns true(https://github.com/intel/llvm-test-suite/blob/intel/SYCL/BFloat16/bfloat16_builtins.cpp#L41) which means "check" should return true when result and reference value doesn't math. The corrected version should be:
bool check(bool a, bool b) { return (a != b); }

Previously, the code is
bool check(bool a, bool b) { return (a == b); }

[GeorgeWeb]

Hi @jinge90, we were looking into this too and we're pleased to see this patch.

[jinge90]

Hi, @intel/dpcpp-tools-reviewers
Could you help review this PR?
Thanks very much.

[GeorgeWeb]

Hi @intel/dpcpp-tools-reviewers / @AlexeySachkov 👋. Would it be possible to review and merge this?
Thank youi!

[sarnex]

No merge permission though, sorry :)