ctrl + alt + shift + / (cmd + alt + shift + / on MacOS) should show you the following dialog:

http://i.stack.imgur.com/YZ5Ax.png

Clicking on Registry you will get

http://i.stack.imgur.com/LC1p9.png

The key you want to enable/disable is

editor.skip.copy.and.cut.for.empty.selection

Tested on Linux Ubuntu and MacOS.