demangler: CodeWarrior anonymous structs are incorrectly invalid

[vabold]

An example would be RFLiInitShapeRes__FPstruct. One possible implementation could be RFLiInitShapeRes(anonymous struct*).

I'm also not sure if this behavior extends to anonymous unions or anonymous enums. Enums scoped specifically within a file (for example, with this complicated symbol @LOCAL@RFLiGetTexSize__F26@enum$3112RFL_NANDLoader_cUs@scParts2Arc) seem to work fine, albeit with no real demangling, but they don't when they're unscoped.

[muff1n1634]

duplicate of cwdemangle#3, where any further issues like this should go