Assignments within conditional expressions should kill widened bounds

[secure-sw-dev-bot]

This issue was copied from checkedc/checkedc-clang#895

---

Expressions within a conditional operator that modify variables used in a widened bounds expression currently do not kill the widened bounds. For example,

void f(nt_array_ptr<char> p : count(i), unsigned i, int flag) {
  if (*(p + i)) {
    // The i++ expression should kill the widened bounds of p.
    flag ? i++ : i;
  }
}

[secure-sw-dev-bot]

Comment from @mgrang:

Fixed in checkedc/checkedc-clang#898

[secure-sw-dev-bot]

Comment from @mgrang:

@kkjeer Could you please verify if the above PR fixes the issue?