[utils] Process attribute references in lines defining attrs.

[vzakhari]

Here is an example of TBAA attributes generated by Flang:

#tbaa_root = #llvm.tbaa_root<id = "Flang function root _QPtest6">
#tbaa_type_desc = #llvm.tbaa_type_desc<id = "any access", members = {<#tbaa_root, 0>}>

We have to process the text after = to replace the attribute
references with proper check variables.

[vzakhari]

@abidh @tblah I think you might have hit the issue that the checks generator script does not fully automate the attributes matching (e.g. for TBAA and debug attributes that Flang generates). Please take a look, and let me know if this change would be useful to you.

[tblah]

Yes this would be useful for me thank you. If I remember right I had to do these manually. Are there no lit tests for generate-test-checks.py?

[vzakhari]

Yes this would be useful for me thank you. If I remember right I had to do these manually. Are there no lit tests for generate-test-checks.py?

I could not find existing tests for this script.

[tblah]

Thanks for this