be safe to handle operator= (#18850)

* 等号赋值函数，先判断this是否不等于other再做赋值

1、CCData那个会闪退
2、CCGLProgramState那个会造成_value.tex.texture泄漏

* replace TAB to  4 SPACE

cocos/base/CCData.cpp

@@ -61,16 +61,22 @@ Data::~Data()
 }
 
 Data& Data::operator= (const Data& other)
+{
+    if (this != &other)
     {
         CCLOGINFO("In the copy assignment of Data.");
         copy(other._bytes, other._size);
+    }
     return *this;
 }
 
 Data& Data::operator= (Data&& other)
+{
+    if (this != &other)
     {
         CCLOGINFO("In the move assignment of Data.");
         move(other);
+    }
     return *this;
 }
 

cocos/renderer/CCGLProgramState.cpp

@@ -272,6 +272,8 @@ void UniformValue::setMat4(const Mat4& value)
 }
 
 UniformValue& UniformValue::operator=(const UniformValue& o)
+{
+    if (this != &o)
     {
         _uniform = o._uniform;
         _glprogram = o._glprogram;
@@ -282,6 +284,7 @@ UniformValue& UniformValue::operator=(const UniformValue& o)
         {
             CC_SAFE_RETAIN(_value.tex.texture);
         }
+    }
     return *this;
 }