This fixes the regression of several tests on Windows after rL258621.
The root problem is that ObjectFilePECOFF was not setting type information for the symbols, and the new CL rejects symbols without type information, breaking functionality like thread step-over.
The fix sets the type information for functions (and creates a TODO for other types).
Along the way, I fixed some typos and formatting that made the code I was debugging harder to understand.
In the long run, we should consider replacing most of ObjectFilePECOFF with the COFF parsing code from LLVM.