[clang] [Mips] Correctly define IntPtrType (PR #145158)

[Alex Rønne Petersen via cfe-commits]

alexrp wrote:

FWIW, this appears to fix a compilation error in LLVM for `mips-netbsd`:

```
/home/alexrp/Source/ziglang/zig-bootstrap/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp:444:26: error: no matching function for call to 'min'
  444 |     UsedByIndices.resize(std::min(UsedByIndices.size(), LastLUIdx));
```

(No idea why that only happened for NetBSD and not e.g. Linux.)

https://github.com/llvm/llvm-project/pull/145158