[cocos2dx] Closes #1734, simplify file I/O.

spine-cocos2dx/src/spine/spine-cocos2dx.cpp

@@ -167,7 +167,7 @@ Cocos2dExtension::Cocos2dExtension() : DefaultSpineExtension() { }
 Cocos2dExtension::~Cocos2dExtension() { }
 
 char *Cocos2dExtension::_readFile(const spine::String &path, int *length) {
-	Data data = FileUtils::getInstance()->getDataFromFile(FileUtils::getInstance()->fullPathForFilename(path.buffer()));
+    Data data = FileUtils::getInstance()->getDataFromFile(path.buffer());
 	if (data.isNull()) return nullptr;
 
 	// avoid buffer overflow (int is shorter than ssize_t in certain platforms)