Hexagon: Initialize TBB to 0.

Found by valgrind.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156744 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/Hexagon/HexagonInstrInfo.cpp b/lib/Target/Hexagon/HexagonInstrInfo.cpp
index b6ec8e1..eba6ab5 100644
--- a/lib/Target/Hexagon/HexagonInstrInfo.cpp
+++ b/lib/Target/Hexagon/HexagonInstrInfo.cpp
@@ -171,6 +171,7 @@
                                  MachineBasicBlock *&FBB,
                                  SmallVectorImpl<MachineOperand> &Cond,
                                  bool AllowModify) const {
+  TBB = NULL;
   FBB = NULL;
 
   // If the block has no terminators, it just falls into the block after it.