explicit specialization to a warning for C++98 mode (this is a defect report
resolution, so per our informal policy it should apply in C++98), and turn
the warning on by default for C++11 and later. In all cases where it fires, the
right thing to do is to remove the pointless explicit instantiation.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@280308 91177308-0d34-0410-b5e6-96231b3b80d8