[MachineVerifier] Drop a spurious const

As of r298987 the argument is a value that we std::move, so it
shouldn't be const anymore.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@298999 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed