Add .loc methods to the streamer.

Next: Add support for the !HasDotLocAndDotFile case to the MCAsmStreamer
and then switch codegen to use it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119384 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCNullStreamer.cpp b/lib/MC/MCNullStreamer.cpp
index b95a4f6..c781fe6 100644
--- a/lib/MC/MCNullStreamer.cpp
+++ b/lib/MC/MCNullStreamer.cpp
@@ -83,7 +83,12 @@
                                    unsigned char Value = 0) {}
     
     virtual void EmitFileDirective(StringRef Filename) {}
-    virtual void EmitDwarfFileDirective(unsigned FileNo,StringRef Filename) {}
+    virtual bool EmitDwarfFileDirective(unsigned FileNo,StringRef Filename) {
+      return false;
+    }
+    virtual void EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
+                                       unsigned Column, unsigned Flags,
+                                       unsigned Isa, unsigned Discriminator) {}
     virtual void EmitInstruction(const MCInst &Inst) {}
 
     virtual void Finish() {}