MCSymbolGOFF: Remove classof

The object file format specific derived classes are used in context
where the type is statically known. We don't use isa/dyn_cast and we
want to eliminate MCSymbol::Kind in the base class.

Author: MaskRay

llvm/include/llvm/MC/MCSymbolGOFF.h

@@ -47,8 +47,6 @@ class MCSymbolGOFF : public MCSymbol {
     AssociatedDataArea->RequiresNonZeroLength = true;
   }
   MCSectionGOFF *getADA() const { return ADA; }
-
-  static bool classof(const MCSymbol *S) { return S->isGOFF(); }
 };
 } // end namespace llvm
 

llvm/lib/MC/GOFFObjectWriter.cpp

@@ -345,7 +345,7 @@ void GOFFWriter::defineSymbols() {
   for (const MCSymbol &Sym : Asm.symbols()) {
     if (Sym.isTemporary())
       continue;
-    auto &Symbol = cast<MCSymbolGOFF>(Sym);
+    auto &Symbol = static_cast<const MCSymbolGOFF &>(Sym);
     if (Symbol.hasLDAttributes()) {
       Symbol.setIndex(++Ordinal);
       defineLabel(Symbol);