[RFC][PATCH] malloc: Fix test for malloc_usable_size

[DJ Delorie]

Matheus Castanho <msc@linux.ibm.com> writes:
> We have seen some tests on recent builds on ppc64le failing with
> the following:
>
>   ---=== ./malloc/tst-malloc-usable-tunables.out ===---
>   malloc_usable_size: expected 7 but got 24
>   FAIL: malloc/tst-malloc-usable-tunables.c

The root cause here is much more insidious.

See https://bugzilla.redhat.com/show_bug.cgi?id=1659276

Basically, tunables has a bug-er-design-issue, and without the right
tunables, the malloc test can't work right anyway.

See also https://sourceware.org/bugzilla/show_bug.cgi?id=25035

Fix imminent :-)