Add dummy fields to structure types only if they are actually empty.
Add dummy fields to structure types only if they are actually empty.

Class objects and unions will never be empty because of compiler
inserted fields.



git-svn-id: 88467cb1fb04b8a755be7e1ee1026be4190196ef@16447 3a8e244f-b0f2-452b-bcba-4c88e055c3ca

sungeunchoi/chapel,CoryMcCartan/chapel,sungeunchoi/chapel,sungeunchoi/chapel,chizarlicious/chapel,chizarlicious/chapel,CoryMcCartan/chapel,hildeth/chapel,hildeth/chapel,sungeunchoi/chapel,sungeunchoi/chapel,CoryMcCartan/chapel,chizarlicious/chapel,hildeth/chapel,hildeth/chapel,CoryMcCartan/chapel,chizarlicious/chapel,CoryMcCartan/chapel,sungeunchoi/chapel,chizarlicious/chapel,hildeth/chapel,CoryMcCartan/chapel,sungeunchoi/chapel,chizarlicious/chapel,hildeth/chapel,chizarlicious/chapel,CoryMcCartan/chapel,sungeunchoi/chapel,hildeth/chapel