rewrite_union no longer needs namespace

[kroening]

Depends on #2697. Look at last commit only.

[tautschnig]

I believe rewrite_union never needed a namespace in the first place, and the changes proposed here should actually be safe even without all the ID_union_tag work. I'd propose to rebase the new commit onto develop, making the PR truly independent.

[kroening]

Unfortunately, it does need the namespace right now, or you can't look up whether the symbol_type is a union or a struct.

[tautschnig]

Unfortunately, it does need the namespace right now, or you can't look up whether the symbol_type is a union or a struct.

Oh yes, sorry.

Could this one be rebased onto the latest version of of #2697 or those commits be cherry-picked in here for CI to succeed?

[tautschnig]

The depended-on commit has been merged, should be ready to go once rebased.

[kroening]

Rebase done

[allredj]

Passed Diffblue compatibility checks (cbmc commit: 7170711).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/84131501