llvm-mc: Add const to EmitZeroFill section argument.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80341 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCNullStreamer.cpp b/lib/MC/MCNullStreamer.cpp
index 61a9d49..14534ed 100644
--- a/lib/MC/MCNullStreamer.cpp
+++ b/lib/MC/MCNullStreamer.cpp
@@ -46,7 +46,7 @@
     virtual void EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
                                   unsigned Pow2Alignment, bool IsLocal) {}
 
-    virtual void EmitZerofill(MCSection *Section, MCSymbol *Symbol = NULL,
+    virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
                               unsigned Size = 0, unsigned Pow2Alignment = 0) {}
 
     virtual void EmitBytes(const StringRef &Data) {}