PR middle-end/105604 - ICE: in tree_to_shwi with vla in struct and sprintf

PR middle-end/105604 - ICE: in tree_to_shwi with vla in struct and sprintf

gcc/ChangeLog:

	PR middle-end/105604
	* gimple-ssa-sprintf.cc (set_aggregate_size_and_offset): Add comments.
	(get_origin_and_offset_r): Remove null handling.  Handle variable array
	sizes.
	(get_origin_and_offset): Handle null argument here.  Simplify.
	(alias_offset): Update comment.
	* pointer-query.cc (field_at_offset): Update comment.  Handle members
	of variable-length types.

gcc/testsuite/ChangeLog:

	PR middle-end/105604
	* gcc.dg/Wrestrict-24.c: New test.
	* gcc.dg/Wrestrict-25.c: New test.
	* gcc.dg/Wrestrict-26.c: New test.

Co-authored-by: Richard Biener <rguenther@suse.de>
(cherry picked from commit 10d1986aee47c592f903527bb68546efc557735d)