symtab.c (symtab_node::equal_address_to): Return -1 instead of 2 if we can't determine address equivalence.

	* symtab.c (symtab_node::equal_address_to): Return -1 instead of 2
	if we can't determine address equivalence.
	* alias.c (compare_base_decl): Update for changed return value of
	symtab_node::equal_address_to.

From-SVN: r232172