[llvm] [SPIRV] Handle `inttoptr` constant expressions in global initialisers (PR #166494)

[Juan Manuel Martinez Caamaño via llvm-commits]

================
@@ -1210,8 +1210,16 @@ bool SPIRVInstructionSelector::selectUnOp(Register ResVReg,
     for (MachineRegisterInfo::def_instr_iterator DefIt =
              MRI->def_instr_begin(SrcReg);
          DefIt != MRI->def_instr_end(); DefIt = std::next(DefIt)) {
-      if ((*DefIt).getOpcode() == TargetOpcode::G_GLOBAL_VALUE ||
-          (*DefIt).getOpcode() == SPIRV::OpVariable) {
+      unsigned DefOpCode = (*DefIt).getOpcode();
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jmmartinez wrote:

NIT
```suggestion
      unsigned DefOpCode = DefIt->getOpcode();
```

https://github.com/llvm/llvm-project/pull/166494