osi_linux/kernelinfo_gdb: Ignore print_offset() errors

[be32826]

Fixes part of #1422. If a struct field is deleted, kernelinfo_gdb will do the best it can instead of erroring and outputting nothing. Higher-level plugins that need to get a list of threads and need to be compatible with newer kernels can implement their own handling on top of this.

[lacraig2]

I don't think this is the right approach.

The parser here provides an error because osi_linux requires that field as part of its profile. If you simply bypass the error you'll generate invalid profiles (i.e. osi_linux can't start up with them).

A better approach would be to see how this field contributes to osi_linux logic, ensure it handles the case that it is not present, and then mark this field optional (e.g. as with start_time example) and change the corresponding script to handle that.

[AndrewFasano]

Perhaps there's some middle ground? It might be nice to have the config-generator support creating partial configs when fields are unavailable instead of having to patch it every time we want to make something optional? Perhaps a warning being generated along the lines of Field X is missing - this may cause an error with OSI Linux. Or maybe a flag like --skip-missing that turns these errors into a warning?

Then, to fix #1422 we'll need to update OSI Linux itself to work without this information.

[be32826]

I have a patch for fixing osi_linux with newer kernels and I will make a PR soon, but this change is one part of the fix. If we aren't going to merge this, should I put everything in one PR, or is there a better way to have optional fields with kernelinfo_gdb?