Fix --disable-threads build, PR7949.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111676 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/System/ThreadLocal.cpp b/lib/System/ThreadLocal.cpp
index b84a8e7..f6a55a1 100644
--- a/lib/System/ThreadLocal.cpp
+++ b/lib/System/ThreadLocal.cpp
@@ -27,6 +27,7 @@
 ThreadLocalImpl::~ThreadLocalImpl() { }
 void ThreadLocalImpl::setInstance(const void* d) { data = const_cast<void*>(d);}
 const void* ThreadLocalImpl::getInstance() { return data; }
+void ThreadLocalImpl::removeInstance() { data = 0; }
 }
 #else