code for handling triviality, deletedness and constexpr. Fix a few bugs in
these, particularly related to mutable members, and remove some dead code.
llvm-svn: 195809
constexpr until we get to the end of the class definition. When that happens,
be sure to remember that the class actually does have a constexpr constructor.
This is a stopgap solution, which still doesn't cover the case of a class with
multiple copy constructors (only some of which are constexpr). We should be
performing constructor lookup when implicitly defining a constructor in order
to determine whether all constructors it invokes are constexpr.
llvm-svn: 158228