IfWhen we emit `.use llc or lld to compiler IR files, module` or `.nan` for all functions in a single build unit,the features +nan2008 and +fpxx/+fp64 are not used.
GNU as complains: .module is not permitted after generating codeThus wrong format files are produced.
So we should only emit them for the first function in `emitFunctionEntryLabel`In IR files, the attributes are only set for function while not the whole compile units.
So we extract the attributes from the first function and use it for the whole unit.
isFPXXDefault: for o32, the FPXX should always be the default, no matter about the vendors.
Of course some distributions with FP64 default enabled should be listed explicit.
Let's add them in future if we know about one.