Minor fixups for auto deduction of initializer lists.

Fix some review comments.
Add a test for deduction when std::initializer_list isn't available yet.
Fix redundant error messages. This fixes and outstanding FIXME too.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@148735 91177308-0d34-0410-b5e6-96231b3b80d8
10 files changed