Add test that checks whether the expression evaluator can handle
the `NS_ENUM`/`NS_OPTIONS` typedefs from Objective-C `CoreFoundation`.
In the test, `module.h` mimicks the `NS_OPTIONS` typedef from `CoreFoundation`.
The `ClangModulesDeclVendor` currently compiles modules as
C++, so the `MyInt` Clang decl in the module will be a `TypedefType`,
while the DWARF AST parser will produce an `EnumType` (since that's what
the debug-info says). When the `ASTImporter` imports these decls into the
scratch AST, it will fail to re-use one or the other decl because they
aren't structurally equivalent (one is a typedef, the other an enum),
so we end up with two conflicting `MyInt` declarations in the scratch AST
and the expression fails to run due to ambiguity in name lookup.
rdar://151022173
95b5b6801c