Refactor checks for unevaluated contexts into a common utility function.

The one caller that's surrounded by nearby code manipulating the underlying
evaluation context list is left unmodified for readability.

Review by Sean Silva and Richard Smith.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@161355 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed