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.

llvm-svn: 120767
diff --git a/llvm/lib/MC/MCNullStreamer.cpp b/llvm/lib/MC/MCNullStreamer.cpp
index c79793c..86ab628 100644
--- a/llvm/lib/MC/MCNullStreamer.cpp
+++ b/llvm/lib/MC/MCNullStreamer.cpp
@@ -44,6 +44,9 @@
 
     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){}