Implements a virtual destructor on the BaseRequestHandler class.
Implements a virtual destructor on the BaseRequestHandler class to protect against undefined behavior in the event that a derived BaseRequestHandler class has a destructor and an object of such derived class is destroyed through a pointer to its base class.
Backport of core PR12050
Note: the event described above actually occurs.
Build with Clang and check there is no -Wdelete-non-virtual-dtor
With ASAN enabled:
Reviewers: #bitcoin_abc, deadalnix
Reviewed By: #bitcoin_abc, deadalnix
Differential Revision: https://reviews.bitcoinabc.org/D3605