CompilationDatabase_Error is an error and should be the last return argument

[zimmski]

FromDirectory has an return argument of type CompilationDatabase_Error which should be the last argument because it is an error and the Go idiom is to put errors last, even if they are user defined types.

Look through all version repositories if there are more instances of this kind of API inconsistency, e.g. LoadDiag_Error was easy to find