IRGen: Add more tests for dll attributes

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@209596 91177308-0d34-0410-b5e6-96231b3b80d8
Sema: Add dll attribute tests for variable templates

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@209597 91177308-0d34-0410-b5e6-96231b3b80d8
Sema: Add dll attribute tests for member functions

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@209598 91177308-0d34-0410-b5e6-96231b3b80d8