add [cd]tors to scc_info

gcc/ChangeLog:

2016-07-26  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>

	* tree-ssa-structalias.c (struct scc_info): Change types of
	members to auto_sbitmap and auto_vec.
	(scc_info::scc_info): New constructor.
	(scc_info::~scc_info): New destructor.
	(init_scc_info): Remove.
	(free_scc_info): Remove.
	(find_indirect_cycles): Adjust.
	(perform_var_substitution): Likewise.
	(free_var_substitution_info): Likewise.

From-SVN: r238751