Add a std::string Wrapper for TableGen

Create a std::string wrapper for use as a DenseMap key.  DenseMap is
not safe in generate with strings, so this wrapper indicates that only
strings guaranteed not to have certain values should be used in the
DenseMap.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136481 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed