Switch FoldingSet::AddString to StringRef based API.
 - This also fixes a dereference of std::string::end, which makes MSVC unhappy and was causing all the static analyzer clang tests to fail.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82517 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed