[CodeGen] Disable default copy ctor and copy assignment operator for …

…class Array

class Array manages resources such as dynamically allocated memory, it's generally a good practice to either implement a custom copy constructor or disable the default one.

Reviewed By: pengfei

Differential Revision: https://reviews.llvm.org/D152231

llvm/include/llvm/CodeGen/LiveIntervalUnion.h

@@ -174,6 +174,8 @@ class LiveIntervalUnion {
 
   public:
     Array() = default;
+    Array &operator=(const Array &other) = delete;
+    Array(const Array &other) = delete;
     ~Array() { clear(); }
 
     // Initialize the array to have Size entries.