Pack MCSymbol::HasName in to a spare bit in the section/fragment union.

This is part of an effort to pack the average MCSymbol down to 24 bytes.

The HasName bit was pushing the size of the bitfield over to another word,
so this change uses a PointerIntPair to fit in it to unused bits of a
PointerUnion.

Reviewed by Rafael Espíndola

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241115 91177308-0d34-0410-b5e6-96231b3b80d8

lib/MC/MCSymbol.cpp

@@ -45,7 +45,7 @@ void MCSymbol::setVariableValue(const MCExpr *Value) {
          "Cannot give common/offset symbol a variable value");
   this->Value = Value;
   SymbolContents = SymContentsVariable;
-  SectionOrFragment = nullptr;
+  setUndefined();
 }
 
 void MCSymbol::print(raw_ostream &OS, const MCAsmInfo *MAI) const {