[libunwind] [Mips] Fixed libunwind::Registers_mips_o32::jumpto to allow for load delay (PR #152942)

[Fangrui Song via cfe-commits]

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@@ -1044,9 +1044,10 @@ DEFINE_LIBUNWIND_FUNCTION(_ZN9libunwind18Registers_mips_o326jumptoEv)
   lw    $27, (4 * 27)($4)
   lw    $28, (4 * 28)($4)
   lw    $29, (4 * 29)($4)
-  lw    $30, (4 * 30)($4)
   // load new pc into ra
   lw    $31, (4 * 32)($4)
+  //allow for load delay, so that ra address is new value when jumping
----------------
MaskRay wrote:

Suggest:
```
// MIPS 1 has load delay slot. Ensure lw $31 and jr are separated by an instruction.
```



https://github.com/llvm/llvm-project/pull/152942