[ADT] Adds equality operators for DenseMap and DenseSet, and an initializer_list
constructor for DenseMap (DenseSet already had an initializer_list constructor).

These changes make it easier to migrate existing code that uses std::map and
std::set (which support initializer_list construction and equality comparison)
to DenseMap and DenseSet.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@344522 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed