[Bug tree-optimization/97008] [openacc] Remove invariant that IFN_UNIQUE is last stmt in bb

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97008

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Where's this property used?  grepping finds searches in omp-offload but those
all(?) search the whole instruction stream.