Try to resolve symbol differences early, and if successful create a plain

data fragment. This reduces the time to assemble the test in 8711 from 60s to
54s.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120767 91177308-0d34-0410-b5e6-96231b3b80d8

lib/MC/MCNullStreamer.cpp

@@ -44,6 +44,9 @@ namespace {
 
     virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {}
     virtual void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol){}
+    virtual void EmitDwarfAdvanceLineAddr(int64_t LineDelta,
+                                          const MCSymbol *LastLabel,
+                                          const MCSymbol *Label) {}
 
     virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute){}