[Clang][Driver] Disable ITT annotations in device code by default

[uditagarwal97]

ITT annotations bloats the device code while offering limited benefit to the end user. That's why, this PR disables ITT annotations by default.
After this change, to enable ITT annotations, we would have to use -fsycl-instrument-device-code CLI option.

[bader]

ITT annotations bloats the device code while offering limited benefit to the end user.

@uditagarwal97, can you expand on that? My understanding that external tools like Intel Inspector rely on these annotations. Did you coordinate this change with oneAPI tools teams?

[bashbaug]

Note, the ITT annotation functions are currently marked optnone and hence require the the SPIR-V OptNone function control bit, which not all SPIR-V consumers support. This means that disabling the ITT annotations by default will also result in more portable SPIR-V modules by default.

I agree with this change making the ITT annotations opt-in (for users that want this functionality), rather than opt-out.

[uditagarwal97]

Removed this change from -fpreview-breaking-changes after internal discussion

[Andy51]

Looks good from VTune POV. ITT generally does not work for XPU kernels and even if the target device is CPU the execution is done through OpenCL so it would not have worked anyway.

[mdtoguchi]

Just some comments on test updates - nothing blocking.

[uditagarwal97]

Just some comments on test updates - nothing blocking.

Fixed in 65a6a64

[mdtoguchi]

Thanks - LGTM

[uditagarwal97]

@intel/llvm-gatekeepers the PR is ready to be merged.