Fix the build on Windows.

arc.mm

@@ -56,9 +56,12 @@ static inline arc_tls_key_t arc_tls_key_create(arc_cleanup_function_t cleanupFun
 arc_tls_key_t ARCThreadKey;
 #endif
 
-extern struct objc_class _NSConcreteMallocBlock;
-extern struct objc_class _NSConcreteStackBlock;
-extern struct objc_class _NSConcreteGlobalBlock;
+extern "C"
+{
+	extern struct objc_class _NSConcreteMallocBlock;
+	extern struct objc_class _NSConcreteStackBlock;
+	extern struct objc_class _NSConcreteGlobalBlock;
+}
 
 @interface NSAutoreleasePool
 + (Class)class;
@@ -639,10 +642,23 @@ struct malloc_allocator
 	{
 		return static_cast<T*>(malloc(sizeof(T) * n));
 	}
+
 	void deallocate(T* p, std::size_t)
 	{
 		free(p);
 	}
+
+	template<typename X>
+	malloc_allocator &operator=(const malloc_allocator<X>&) const
+	{
+		return *this;
+	}
+
+	bool operator==(const malloc_allocator &) const
+	{
+		return true;
+	}
+
 	template<typename X>
 	operator malloc_allocator<X>() const
 	{

class.h

@@ -4,6 +4,11 @@
 #include "objc/runtime.h"
 #include <stdint.h>
 
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
 /**
  * Overflow bitfield.  Used for bitfields that are more than 63 bits.
  */
@@ -443,4 +448,7 @@ void freeIvarLists(Class aClass);
  */
 void freeMethodLists(Class aClass);
 
+#ifdef __cplusplus
+} // extern "C"
+#endif
 #endif //__OBJC_CLASS_H_INCLUDED