[SampleProfileInference] Work around odr-use of const non-inline static data...

[SampleProfileInference] Work around odr-use of const non-inline static data member to fix -O0 builds after D120508

MinBaseDistance may be odr-used by std::max, leading to an undefined symbol linker error:

```
ld.lld: error: undefined symbol: (anonymous namespace)::MinCostMaxFlow::MinBaseDistance
>>> referenced by SampleProfileInference.cpp:744 (/home/ray/llvm-project/llvm/lib/Transforms/Utils/SampleProfileInference.cpp:744)
>>>               lib/Transforms/Utils/CMakeFiles/LLVMTransformUtils.dir/SampleProfileInference.cpp.o:((anonymous namespace)::FlowAdjuster::jumpDistance(llvm::FlowJump*) const)
```

Since llvm-project is still using C++ 14, workaround it with a cast.