Use ExprMutationAnalyzer in performance-unnecessary-value-param

Summary:
This yields better recall as ExprMutationAnalyzer is more accurate.

One common pattern this check is now able to catch is:
```
void foo(std::vector<X> v) {
  for (const auto& elm : v) {
    // ...
  }
}
```

Reviewers: george.karpenkov

Subscribers: a.sidorin, cfe-commits

Differential Revision: https://reviews.llvm.org/D50102

llvm-svn: 338903