Fix compilation without pthreads.

Patch by Xerxes Ranby.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74283 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/System/Unix/ThreadLocal.inc b/lib/System/Unix/ThreadLocal.inc
index 6ee840d..83d554d 100644
--- a/lib/System/Unix/ThreadLocal.inc
+++ b/lib/System/Unix/ThreadLocal.inc
@@ -20,6 +20,6 @@
 using namespace sys;
 ThreadLocalImpl::ThreadLocalImpl() { }
 ThreadLocalImpl::~ThreadLocalImpl() { }
-void ThreadLocalImpl::setInstance(void* d) { data = d; }
-void* ThreadLocalImpl::getInstance() { return data; }
-}
\ No newline at end of file
+void ThreadLocalImpl::setInstance(const void* d) { data = const_cast<void*>(d);}
+const void* ThreadLocalImpl::getInstance() { return data; }
+}