brw: Avoid reading past the end of p->store

On the last iteration of the loop, `offset` will point to the location
just beyond the last instruction in the program. If the program exactly
fills `p->store` then calling `next_offset()` will read out of bounds.

Instead just let the inner while loop call `next_offset()` one
additional time.

Fixes: a35b9cb625 ("i965: Add annotation data structure and support code.")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/12486
Reviewed-by: Caio Oliveira <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33101>

src/intel/compiler/brw_eu_compact.c

@@ -2498,8 +2498,6 @@ brw_compact_instructions(struct brw_codegen *p, int start_offset,
          }
 
          group->offset = start_offset + offset;
-
-         offset = next_offset(devinfo, store, offset);
       }
    }