[llvm] Delete assignment operator from `MachineBlockFrequencyInfo` (PR #101289)

[Shengchen Kan via llvm-commits]

KanRobert wrote:

> > > Since the `MachineBlockFrequencyInfo` class has an overloaded copy constructor, the assignment operator should be deleted to prevent undefined behaviour
> > 
> > 
> > `has an overloaded copy constructor` where, could you point out?
> 
> The above `MachineBlockFrequencyInfo(MachineBlockFrequencyInfo &&);`

Okay. I think it's called move constructor...

https://github.com/llvm/llvm-project/pull/101289