This commit adds a node handle type, (located in __node_handle), and adds
extract() and insert() members to all map and set types, as well as their
implementations in __tree and __hash_table.
The second half of this feature is adding merge() members, which splice nodes
in bulk from one container into another. This will be committed in a follow-up.
Differential revision: https://reviews.llvm.org/D46845
llvm-svn: 338472
Replace unary_function inheritance (which was never required,
even in C++98) with argument_type and result_type typedefs.
This increases portability, as unary_function was removed in C++17
and MSVC has implemented that removal.
Fixes D45596.
llvm-svn: 329974