[MC][ELF] Fix unused variable warning (NFC)

GCC warning:
```
/llvm-project/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp: In member function ‘virtual llvm::MCSection* llvm::TargetLoweringObjectFileELF::getSectionForLSDA(const llvm::Function&, const llvm::MCSymbol&, const llvm::TargetMachine&) const’:
/llvm-project/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp:871:8: warning: variable ‘IsComdat’ set but not used [-Wunused-but-set-variable]
  871 |   bool IsComdat = false;
      |        ^~~~~~~~
```

Author: nullptr-cpp

llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp

@@ -868,11 +868,9 @@ MCSection *TargetLoweringObjectFileELF::getSectionForLSDA(
   unsigned Flags = LSDA->getFlags();
   const MCSymbolELF *LinkedToSym = nullptr;
   StringRef Group;
-  bool IsComdat = false;
   if (const Comdat *C = getELFComdat(&F)) {
     Flags |= ELF::SHF_GROUP;
     Group = C->getName();
-    IsComdat = C->getSelectionKind() == Comdat::Any;
   }
   // Use SHF_LINK_ORDER to facilitate --gc-sections if we can use GNU ld>=2.36
   // or LLD, which support mixed SHF_LINK_ORDER & non-SHF_LINK_ORDER.