Voting for a lesser evil is still voting for evil. You can always choose not to vote or vote for a candidate that does not have a chance of winning.
We might not be able to elect a libertarian, green, constitution, or whig president in 2016, but just as the erosion of our freedoms has taken decades, we'll have to rebuild everything just as slowly. Vote for your preferred candidate this primary. You may not be on "the winning team" today, but you're sending a message that the status quo is not what we want.