Fix the build on OpenBSD.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74597 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/System/ThreadLocal.cpp b/lib/System/ThreadLocal.cpp
index 8884e79..b0c7fa5 100644
--- a/lib/System/ThreadLocal.cpp
+++ b/lib/System/ThreadLocal.cpp
@@ -44,7 +44,7 @@
   int errorcode = pthread_key_create(key, NULL);
   assert(errorcode == 0);
   (void) errorcode;
-  data = key;
+  data = static_cast<void*>(key);
 }
 
 ThreadLocalImpl::~ThreadLocalImpl() {