This patch fixes a bug in which summarized state dumps involving a
non-NULL pointer to a region for which get_representative_path_var
returned NULL were erroneously dumped as "NULL".

It also extends sm-state dumps so that they show representative tree
values, where available.

Finally, it adds some selftest coverage for such dumps.  Doing so
requires replacing some %qE with a dump_quoted_tree, to avoid
C vs C++ differences between "make selftest-c" and "make selftest-c++".

gcc/analyzer/ChangeLog:
	* analyzer.h (dump_quoted_tree): New decl.
	* engine.cc (exploded_node::dump_dot): Pass region model to
	sm_state_map::print.
	* program-state.cc: Include diagnostic-core.h.
	(sm_state_map::print): Add "model" param and use it to print
	representative trees.  Only print origin information if non-null.
	(sm_state_map::dump): Pass NULL for model to print call.
	(program_state::print): Pass region model to sm_state_map::print.
	(program_state::dump_to_pp): Use spaces rather than newlines when
	summarizing.  Pass region_model to sm_state_map::print.
	(ana::selftest::assert_dump_eq): New function.
	(ASSERT_DUMP_EQ): New macro.
	(ana::selftest::test_program_state_dumping): New function.
	(ana::selftest::analyzer_program_state_cc_tests): Call it.
	* program-state.h (program_state::print): Add model param.
	* region-model.cc (dump_quoted_tree): New function.
	(map_region::print_fields): Use dump_quoted_tree rather than
	%qE to avoid lang-dependent output.
	(map_region::dump_child_label): Likewise.
	(region_model::dump_summary_of_map): For SK_REGION, when
	get_representative_path_var fails, print the region id rather than
	erroneously printing NULL.
	* sm.cc (state_machine::get_state_by_name): New function.
	* sm.h (state_machine::get_state_by_name): New decl.