This patch replaces any_cast with llvm::any_cast. This in turn allows us
to gracefully switch to std::any in future by forwarding llvm::Any and
llvm::any_cast to:
using Any = std::any;
template <class T> T *any_cast(Any *Value) {
return std::any_cast<T>(Value);
}
respectively.
Without this patch, it's ambiguous whether any_cast refers to
std::any_cast or llvm::any_cast.
As an added bonus, this patch makes it easier to mechanically replace
llvm::any_cast with std::any_cast without affecting other occurrences of
any_cast (e.g. in libcxx).