importer::findOptionSetEnum() uses some fragile heuristics to determine
whether a typedef is involved in the construction of a CF_OPTIONS or
NS_OPTIONS type. This patch adds an explicit check that the typedef is
expanded from either of those macros, to prevent, e.g., an unavailable
NS_ENUM, from being mistakenly recognized as an NS_OPTIONS.
Note that doing this is still kind of fragile, and prevents users from
building {NS,CF}_OPTIONS with their own macros. The right thing to do is
probably specifically look for the flag_enum attribute, but that is not
currently what we're doing for reasons whose discovery is left as
an exercise to the future git archaeologist.
This patch also removes (part of) a test case that builds
a CF_OPTIONS-like type with the "SOME_OPTIONS" macro, which is no longer
supported as of this patch.
rdar://150399978
