Improvements & fixes in qt_attribution.json (qtbase/src/corelib/text)

I've been using the output of qtattributionscanner to do some further processing.

However I noticed that the value of the paths & files in the output sometimes contain "../"

I don't know if this is intended or if there is a bug in qtattributionscanner in which case this could be fixed there.

The current output is problematic if the tools that use the output don't resolve paths containing ../ parts.

I suggest the changes in the small attached patch, which will permit to have an json output with paths without "../" which can be directly used.