When we use llc or lld to compiler IR files, the features +nan2008 and +fpxx/+fp64 are not used.
Thus wrong format files are produced.
In IR files, the attributes are only set for function while not the whole compile units.
So we output .nan 2008 and .module fp=xx/64 before every function.
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.