PR analyzer/93899 reports an ICE within make_region_for_type when
handling a param of type OFFSET_TYPE within
exploded_graph::add_function_entry.

This patch fixes the ICE by further generalizing the "give up on this
tree code" logic from
  r10-6667-gf76a88eb
     for PR analyzer/93388 and
  r10-6695-g2e623393
     for PR analyzer/93778
by replacing the gcc_unreachable in make_region_for_type with a return
of NULL, and handling this in add_region_for_type by notifying the ctxt.

Doing so means that numerous places that create regions now need to have
a context passed to them, so most of the patch is churn involved in
passing a context around to where it's needed.

gcc/analyzer/ChangeLog:
	PR analyzer/93899
	* engine.cc
	(impl_region_model_context::impl_region_model_context): Add logger
	param.
	* engine.cc (exploded_graph::add_function_entry): Create an
	impl_region_model_context and pass it to the push_frame call.
	Bail if the resulting state is invalid.
	(exploded_graph::build_initial_worklist): Likewise.
	(exploded_graph::build_initial_worklist): Handle the case where
	add_function_entry fails.
	* exploded-graph.h
	(impl_region_model_context::impl_region_model_context): Add logger
	param.
	* region-model.cc (map_region::get_or_create): Add ctxt param and
	pass it to add_region_for_type.
	(map_region::can_merge_p): Pass NULL as a ctxt to call to
	get_or_create.
	(array_region::get_element): Pass ctxt to call to get_or_create.
	(array_region::get_or_create): Add ctxt param and pass it to
	add_region_for_type.
	(root_region::push_frame): Pass ctxt to get_or_create calls.
	(region_model::get_lvalue_1): Likewise.
	(region_model::make_region_for_unexpected_tree_code): Assert that
	ctxt is non-NULL.
	(region_model::get_rvalue_1): Pass ctxt to get_svalue_for_fndecl
	and get_svalue_for_label calls.
	(region_model::get_svalue_for_fndecl): Add ctxt param and pass it
	to get_region_for_fndecl.
	(region_model::get_region_for_fndecl): Add ctxt param and pass it
	to get_or_create.
	(region_model::get_svalue_for_label): Add ctxt param and pass it
	to get_region_for_label.
	(region_model::get_region_for_label): Add ctxt param and pass it
	to get_region_for_fndecl and get_or_create.
	(region_model::get_field_region): Add ctxt param and pass it to
	get_or_create_view and get_or_create.
	(make_region_for_type): Replace gcc_unreachable with return NULL.
	(region_model::add_region_for_type): Add ctxt param.  Handle a
	return of NULL from make_region_for_type by calling
	make_region_for_unexpected_tree_code.
	(region_model::get_or_create_mem_ref): Pass ctxt to calls to
	get_or_create_view.
	(region_model::get_or_create_view): Add ctxt param and pass it to
	add_region_for_type.
	(selftest::test_state_merging): Pass ctxt to get_or_create_view.
	* region-model.h (region_model::get_or_create): Add ctxt param.
	(region_model::add_region_for_type): Likewise.
	(region_model::get_svalue_for_fndecl): Likewise.
	(region_model::get_svalue_for_label): Likewise.
	(region_model::get_region_for_fndecl): Likewise.
	(region_model::get_region_for_label): Likewise.
	(region_model::get_field_region): Likewise.
	(region_model::get_or_create_view): Likewise.

gcc/testsuite/ChangeLog:
	PR analyzer/93899
	* g++.dg/analyzer/pr93899.C: New test.