Fix for a ARC warning.

Author: slembcke

cocos2d/CCProtocols.h

@@ -50,7 +50,7 @@
 @property(nonatomic, readonly) NSMutableDictionary *shaderUniforms;
 
 /// The rendering state this node will use when rendering.
-@property(nonatomic, readonly) CCRenderState *renderState;
+@property(nonatomic, readonly, strong) CCRenderState *renderState;
 
 @end
 
@@ -75,7 +75,7 @@
 @property(nonatomic, readwrite, strong) CCBlendMode *blendMode;
 
 /// The rendering state this node will use when rendering.
-@property(nonatomic, readonly) CCRenderState *renderState;
+@property(nonatomic, readonly, strong) CCRenderState *renderState;
 
 /** set the source blending function for the texture */
 -(void) setBlendFunc:(ccBlendFunc)blendFunc __attribute__((deprecated));
@@ -103,7 +103,7 @@
 @property(nonatomic, strong) CCTexture *texture;
 
 /// The rendering state this node will use when rendering.
-@property(nonatomic, readonly) CCRenderState *renderState;
+@property(nonatomic, readonly, strong) CCRenderState *renderState;
 
 @end