Client lib: fix gcc compilation by removing redundant virtual declaration.
Client lib: fix gcc compilation by removing redundant virtual declaration.

thebigbrain/qfs,thebigbrain/qfs,qnu/qfs,chanwit/qfs,fengshao0907/qfs,fengshao0907/qfs,thebigbrain/qfs,fengshao0907/qfs,chanwit/qfs,chanwit/qfs,qnu/qfs,qnu/qfs,chanwit/qfs,quantcast/qfs,thebigbrain/qfs,chanwit/qfs,fengshao0907/qfs,fengshao0907/qfs,quantcast/qfs,thebigbrain/qfs,quantcast/qfs,chanwit/qfs,qnu/qfs,qnu/qfs,thebigbrain/qfs,qnu/qfs,qnu/qfs,chanwit/qfs,thebigbrain/qfs,chanwit/qfs,thebigbrain/qfs,fengshao0907/qfs,quantcast/qfs,quantcast/qfs,quantcast/qfs,qnu/qfs,fengshao0907/qfs,quantcast/qfs,quantcast/qfs,fengshao0907/qfs