Adding the Subjects entry back for the noreturn attributes. This caused some test cases to be updated because the original diagnostic was about applying to methods as well as functions, but the semantic checking disallowed methods.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@195862 91177308-0d34-0410-b5e6-96231b3b80d8