Satisfy C++ aliasing rules, per suggestion by Chandler.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158346 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/ThreadLocal.cpp b/lib/Support/ThreadLocal.cpp
index 1030a2b..17e0fe1 100644
--- a/lib/Support/ThreadLocal.cpp
+++ b/lib/Support/ThreadLocal.cpp
@@ -40,7 +40,7 @@
 namespace llvm {
 using namespace sys;
 
-ThreadLocalImpl::ThreadLocalImpl() : data(0) {
+ThreadLocalImpl::ThreadLocalImpl() : data() {
   typedef int SIZE_TOO_BIG[sizeof(pthread_key_t) <= sizeof(data) ? 1 : -1];
   pthread_key_t* key = reinterpret_cast<pthread_key_t*>(&data);
   int errorcode = pthread_key_create(key, NULL);