These are an artifact of how types are structured but serve little
purpose, merely showing that the type is sugared in some way. For
example, ElaboratedType's existence means struct S gets printed as
'struct S':'struct S' in the AST, which is unnecessary visual clutter.
Note that skipping the second print when the types have the same string
matches what we do for diagnostics, where the aka will be skipped.
Also add 'system-zos' as a lit feature and use it where needed.
Part of the project to eliminate special handling for triples in lit
expressions.
Differential Revision: https://reviews.llvm.org/D139444
AIX and z/OS lack Objective-C support, so mark these tests as unsupported for AIX and z/OS.
Reviewed By: jsji
Differential Revision: https://reviews.llvm.org/D109060
