Assignment operator does not check for self-assignment

Defect 100076 (STATIC_C)
Checker SELF_ASSIGN (subcategory none)
File: /src/mongo/db/clientcursor.cpp
Function mongo::ClientCursorPin::operator =(mongo::ClientCursorPin&&)
/src/mongo/db/clientcursor.cpp, line: 198
No protection against the object assigning to itself.

        _cursor = other._cursor;