SRA: Force gimple operand in an additional corner case (PR 112822)

PR 112822 revealed a corner case in load_assign_lhs_subreplacements
where it creates invalid gimple: an assignment where on the LHS there
is a complex variable which however is not a gimple register because
it has partial defs and on the right hand side there is a
VIEW_CONVERT_EXPR.  This patch invokes force_gimple_operand_gsi on
such statements (like it already does when both sides of a generated
assignment have partial definitions.

gcc/ChangeLog:

2023-12-12  Martin Jambor  <mjambor@suse.cz>

	PR tree-optimization/112822
	* tree-sra.cc (load_assign_lhs_subreplacements): Invoke
	force_gimple_operand_gsi also when LHS has partial stores and RHS is a
	VIEW_CONVERT_EXPR.