Some VDSO instances have their only segment happening to fit on one page, with just section headers and non-loaded sections on the second page. Since those non-loaded sections are still loaded because VDSO is placed completely in memory, this causes some confusion with parts of DR that expect the mapping end to equal the end of the final segment. Our solution is to add a synthetic segment for the rest of the mapping. It's possible this will cause confusion of its own, but it seems the least bad thing to do.
Fixes #3900 (closed)