* 10461 Reject close of vote accounts unless it earned no credits in the previous epoch. This is checked by comparing current epoch (from clock sysvar) with the most recent epoch with credits in vote state.
* Unifies SysvarCache filling in the runtime and tests.
Removes new_mock_with_sysvars_and_features()
Removes mock_process_instruction_with_sysvars().
Replaces from_keyed_account() by SysvarCache in vote processor.
* Replaces from_keyed_account() by SysvarCache in BPF loader.
