[MC] Disable default copy ctor and copy assignment operator for CodeViewContext

[yubing]

Summary

class CodeViewContext 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.

[skan]

LGTM

llvm/include/llvm/MC/MCCodeView.h

 };
 
 /// Holds state from .cv_file and .cv_loc directives for later emission.
 class CodeViewContext {
 public:
   CodeViewContext();
   ~CodeViewContext();
 
+  CodeViewContext &operator=(const CodeViewContext &other) = delete;
+  CodeViewContext(const CodeViewContext &other) = delete;
+
   bool isValidFileNumber(unsigned FileNumber) const;
   bool addFile(MCStreamer &OS, unsigned FileNumber, StringRef Filename,
                ArrayRef<uint8_t> ChecksumBytes, uint8_t ChecksumKind);
 
   /// Records the function id of a normal function. Returns false if the
   /// function id has already been used, and true otherwise.
   bool recordFunctionId(unsigned FuncId);