Improvements to typed_splay_tree

Improvements to typed_splay_tree

This patch adds foreach, max and min methods to
class typed_splay_tree, along with the start of a selftest
suite.

gcc/ChangeLog:
	* Makefile.in (OBJS): Add typed-splay-tree.o.
	* selftest-run-tests.c (selftest::run_tests): Call
	typed_splay_tree_c_tests.
	* selftest.h (typed_splay_tree_c_tests): New decl.
	* typed-splay-tree.c: New file.
	* typed-splay-tree.h (typed_splay_tree::foreach_fn): New typedef.
	(typed_splay_tree::max): New method.
	(typed_splay_tree::min): New method.
	(typed_splay_tree::foreach): New method.
	(typed_splay_tree::closure): New struct.
	(typed_splay_tree::inner_foreach_fn): New function.

From-SVN: r239958