Make it possible for builtins to expression FILE* arguments, so that

Make it possible for builtins to expression FILE* arguments, so that
we can define builtins such as fprintf, vfprintf, and
__builtin___fprintf_chk. Give a nice error message when we need to
implicitly declare a function like fprintf.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@64526 91177308-0d34-0410-b5e6-96231b3b80d8