[Chapel Merge] Support for C unions in c2chapel

Branch: refs/heads/master
Revision: 2790dd1
Author: leekillough
Log Message:

Merge pull request #17499 from leekillough/c2chapel-union

Support for C unions in c2chapel

The c2chapel tool should now support C unions the same way it supports C structs.

Fixes #17278.

[ Author: @souris-dev ]

[ Reviewers: @leekillough @mppf @bradcray ]

Modified Files:
A test/c2chapel/testUnions.c

A test/c2chapel/testUnions.chpl
A test/c2chapel/testUnions.cleanfiles
A test/c2chapel/testUnions.compopts
A test/c2chapel/testUnions.good
A test/c2chapel/testUnions.h
A test/c2chapel/testUnions.precomp
A tools/c2chapel/test/miscTypedefUnion.chpl
A tools/c2chapel/test/miscTypedefUnion.h
A tools/c2chapel/test/nestedUnion.chpl
A tools/c2chapel/test/nestedUnion.h
A tools/c2chapel/test/opaqueUnion.chpl
A tools/c2chapel/test/opaqueUnion.h
M test/c2chapel/c2chapel-tester.good
M tools/c2chapel/c2chapel.py

Compare: https://github.com/chapel-lang/chapel/compare/38f43471f6e2...2790dd16e654