Improve/correct detection of overlapping aggregates [PR102238, PR102919].

Resolves:
PR tree-optimization/102238 - alias_offset in gimple-ssa-sprintf.c is broken
PR tree-optimization/102919 - spurious -Wrestrict warning for sprintf into the same member array as argument plus offset

gcc/ChangeLog:

	PR tree-optimization/102238
	PR tree-optimization/102919
	* gimple-ssa-sprintf.c (get_string_length): Add an argument.
	(array_elt_at_offset): Move to pointer-query.
	(set_aggregate_size_and_offset): New function.
	(field_at_offset):  Move to pointer-query.
	(get_origin_and_offset): Rename...
	(get_origin_and_offset_r): this.  Add an argument.  Make aggregate
	handling more robust.
	(get_origin_and_offset): New.
	(alias_offset): Add an argument.
	(format_string): Use subobject size determined by get_origin_and_offset.
	* pointer-query.cc (field_at_offset): Move from gimple-ssa-sprintf.c.
	Improve/correct handling of aggregates.
	(array_elt_at_offset): Same.
	* pointer-query.h (field_at_offset): Declare.
	(array_elt_at_offset): Declare.

gcc/testsuite/ChangeLog:

	PR tree-optimization/102238
	PR tree-optimization/102919
	* gcc.dg/tree-ssa/builtin-sprintf-warn-23.c: Remove warnings.
	* gcc.dg/Wrestrict-23.c: New test.