sra: Fix build_user_friendly_ref_for_offset for bit-fields (PR124151)

When SRA propagates bit-field propagations across assignments, it
first attempts to use build_user_friendly_ref_for_offset to represent
the expression of the new accesses and a possible scalar replacement
so that if there are any warnings generated for it, they are as nice
as we can make them.

However, this can lead to situations where, despite that the new
access has exactly the same type as the new old one, it accesses a
(record or union): field which is just big enough for its precision,
whereas the one we want to match has size rounded up to bytes.  This
causes discrepancy between the recorded size of the new access and the
size get_ref_base_and_extent reports for its expr, which trips the
verifier.

Unlike the previous approach which avoided propagation in the case of
bit fields, this patch fixes build_user_friendly_ref_for_offset by
making it also track the size it is looking at and the size it is
looking for so that it can declare success only if these two also
match.  Additionally, it reverts the simple bail-out fix for PR 117217
because it is no longer necessary.  (I have verified the bug is still
fixed though by applying the new fix on top of the last problematic
commit.)

gcc/ChangeLog:

2026-04-29  Martin Jambor  <mjambor@suse.cz>

	PR tree-optimization/124151
	* tree-sra.cc (build_user_friendly_ref_for_offset): Added parameters
	CUR_SIZE and EXP_SIZE.  Added code passing the correct CUR_SIZE and
	checking it against EXP_SIZE.  Removed unused code for the case when
	EXP_TYPE was NULL_TREE.
	(create_artificial_child_access): Adjusted the call to
	build_user_friendly_ref_for_offset.
	(propagate_subaccesses_from_rhs): Likewise.
	(propagate_subaccesses_from_rhs): Removed a check that the size of
	lchild is a multiple of BITS_PER_UNIT.
	(propagate_subaccesses_from_lhs): Likewise.

gcc/testsuite/ChangeLog:

2026-04-29  Martin Jambor  <mjambor@suse.cz>

	PR tree-optimization/124151
	* gcc.dg/tree-ssa/pr124151.c: New test.

(cherry picked from commit a202c707bea3ff021b44aa00c0570798a30aae31)