c++: Reimplement static init/fini generation

c++: Reimplement static init/fini generation

Currently we generate static init/fini code by generating a set of
functions taking an 'initp' bool and an unsigned priority.  (There can
be more than one, as we repeat the end-of-compile loop.)  We then
generate a set of real init or fini functions for each needed
prioroty, calling the previous set of functions.  This is of course
very tangled, but excitingly the value-range-propagator is clever
enough to unentangle it.  However, the current arrangement makes
generation awkward, particularly as to how to optimize the
module-global-init generation.

This reimplements the generation to generate a set of separate
init/fini functions for each needed priority, and then call them from
the real inits previously mentioned.  This replaces a splay tree,
recording which priority/init combos we needed, with a pair of hash
tables, mapping priority to init functions.  Much simpler.

While there, rename several of the functions as they are only dealing
with part of the init/fini generation, not the whole set.

	gcc/cp/
	* decl2.cc (struct priority_info_s, priority_info): Delete.
	(priority_map_traits, priority_map_t): New.
	(static_init_fini_fns): New.
	(INITIALIZE_P_IDENTIFIER, PRIORITY_IDENTIFIER): Delete.
	(initialize_p_decl, priority_decl): Delete.
	(ssdf_decls, priority_info_map): Delete.
	(start_static_storage_duration_function): Rename to ...
	(start_partial_init_fini_fn): ... here. Create a void arg fn.
	Add it to the slot in the appropriate static_init_fini_fns
	hash table.
	(finish_static_storage_duration_function): Rename to ...
	(finish_partial_init_fini_fn): ... here.
	(get_priority_info): Delete.
	(one_static_initialization_or_destruction): Assert not
	trivial dtor.
	(do_static_initialization_or_destruction): Rename to ...
	(emit_partial_init_fini_fn) ... here.  Start & finish the fn.
	Simply init/fini each var.
	(partition_vars_for_init_fini): Partition vars according to
	priority and add to init and/or fini list.
	(generate_ctor_or_dtor_function): Start and finish the function.
	Do santitizer calls here.
	(generate_ctor_and_dtor_functions_for_priority): Delete.
	(c_parse_final_cleanups): Reimplement global init/fini
	processing.

	gcc/testsuite/
	* g++.dg/init/static-cdtor1.C: New.