[llvm] [Mips] Fix clang crashes when compiling a variadic function while targeting mips3 (PR #130558)

[Fangrui Song via llvm-commits]

MaskRay wrote:

> > > Because mips3 has the feature 'FeatureGP64
> > 
> > 
> > It seems to apply to newer processors as well.
> 
> Now, I only see mips3 use this feature.
> 
> ```
> def FeatureMips3       : SubtargetFeature<"mips3", "MipsArchVersion", "Mips3",
>                                 "MIPS III ISA Support [highly experimental]",
>                                 [FeatureMips2, FeatureMips3_32,
>                                  FeatureMips3_32r2, FeatureGP64Bit,
>                                  FeatureFP64Bit]>;
> ```

`FeatureMips4` implies `FeatureMips3` and FeatureMips5 implies FeatureMips4, so newer processors get this feature as well.

https://github.com/llvm/llvm-project/pull/130558