Correctly initialize LineSectionSymbol. Thanks to Duncan Sands for noticing it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151979 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCAsmStreamer.cpp b/lib/MC/MCAsmStreamer.cpp
index 742d15d..11f0f72 100644
--- a/lib/MC/MCAsmStreamer.cpp
+++ b/lib/MC/MCAsmStreamer.cpp
@@ -1311,7 +1311,7 @@
 void MCAsmStreamer::FinishImpl() {
   // FIXME: This header is duplicated with MCObjectStreamer
   // Dump out the dwarf file & directory tables and line tables.
-  const MCSymbol *LineSectionSymbol;
+  const MCSymbol *LineSectionSymbol = NULL;
   if (getContext().hasDwarfFiles() && !UseLoc)
     LineSectionSymbol = MCDwarfFileTable::Emit(this);