Consider adding LBT_86  support to box64
Some, but not all(namely, the desktop ones, e.g. 3A6000/3A5000) Loongson CPUs supports native ways of calculating EFLAGS for some x86 instructions and hardware support for x87 stack emulation. Despite the fact that the official documents are not yet published, @jiegec has worked out its semantics, which can be found [here](https://github.com/jiegec/la-inst/blob/master/LBT.md). In theory, this will accelerate box64 in a great deal. Could you please consider adding this feature or give some necessary advice/requirements on how to implement this? e.g. Code style or ways of module integration(runtime loading or simply allow multiple versions by using compilation flags).