RFR: 8263718: unused-result warning happens at os_linux.cpp

[Florian Weimer]

* Thomas Stüfe:

>> I would expect the system thread library to do this if it is beneficial.
>> glibc replaced `COLORING_INCREMENT` (similar to this `alloca`, I believe)
>> with `MULTI_PAGE_ALIASING` on i386 around 2003. `MULTI_PAGE_ALIASING` is
>> implemented in a completely different way; it tweaks stack sizes to avoid
>> accidental higher-level alignment (above the page level) between different
>> threads.
>
> Interesting. Ist this observable (eg via pthread_attr_getstacksize)?

Yes, but that's actually a bug:

  pthread_getattr_np reports wrong stack size with MULTI_PAGE_ALIASING
  <https://sourceware.org/bugzilla/show_bug.cgi?id=23554>

H.J. has just updated the bug, indicating that the code is no longer
needed.

Thanks,
Florian