Add initializer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121262 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMAsmBackend.cpp b/lib/Target/ARM/ARMAsmBackend.cpp
index f5ac33a..615ec4e 100644
--- a/lib/Target/ARM/ARMAsmBackend.cpp
+++ b/lib/Target/ARM/ARMAsmBackend.cpp
@@ -30,7 +30,7 @@
 class ARMAsmBackend : public TargetAsmBackend {
   bool isThumbMode;  // Currently emitting Thumb code.
 public:
-  ARMAsmBackend(const Target &T) : TargetAsmBackend() {}
+  ARMAsmBackend(const Target &T) : TargetAsmBackend(), isThumbMode(false) {}
 
   bool MayNeedRelaxation(const MCInst &Inst) const;