[LoopVer] Add missing std::move

The reason I was passing this vector by value in the constructor so that
I wouldn't have to copy when initializing the corresponding member but
then I forgot the std::move.

The use-case is LoopDistribution which filters the checks then
std::moves it to LoopVersioning's constructor.  With this interface we
can avoid any copies.

llvm-svn: 243616