[fiirl serializer] Fix for #4791

[tobias1012]

Contributor Checklist

• Did you add Scaladoc to every public function/method?
• Did you add at least one test demonstrating the PR?
• Did you delete any extraneous printlns/debugging code?
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Type of Improvement

• Bugfix
• Internal or build-related (includes code refactoring/cleanup)

Desired Merge Strategy

• Squash: The PR will be squashed and merged (choose this if you have no preference).

Release Notes

Fixed improper path escape on windows platform during firrtl serialization. Note the makefile in svsim is still not windows compatible.

Reviewer Checklist (only modified by reviewer)

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[tobias1012]

Looks like old commit already merged got in this pull request too, not sure how to fix.

[tobias1012]

This PR seems to fix the last issue apart from the makefile, however I am having a bit of trouble compiling on windows with the oss-cad-suite as the verilator runtime seems to have trouble finding paths generated by chisel