[PATCH v2] time: Fix overflow itimer tests on 32-bit systems

[Stafford Horne]

On Mon, Aug 16, 2021 at 05:12:04PM +0000, Joseph Myers wrote:
> I'm seeing a build failure in the glibc testsuite for i686-gnu:
> 
> tst-itimer.c: In function 'do_test':
> tst-itimer.c:103:11: error: '__KERNEL_OLD_TIMEVAL_MATCHES_TIMEVAL64' undeclared (first use in this function)
>   103 |       if (__KERNEL_OLD_TIMEVAL_MATCHES_TIMEVAL64)
>       |           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> tst-itimer.c:103:11: note: each undeclared identifier is reported only once for each function it appears in
> 
> https://sourceware.org/pipermail/libc-testresults/2021q3/008412.html

Right sorry about that, so __KERNEL_OLD_TIMEVAL_MATCHES_TIMEVAL64 only exists in
linux.

So it looks like for non linux the new timer test changes break.

Should we provide __KERNEL_OLD_TIMEVAL_MATCHES_TIMEVAL64 for not linux builds,
or remove __KERNEL_OLD_TIMEVAL_MATCHES_TIMEVAL64 from the itimer test again?
The reason for using __KERNEL_OLD_TIMEVAL_MATCHES_TIMEVAL64 is to pick up the
timeval size which is different on each architecture.

Maybe the easiest is adding something like:

#ifndef __KERNEL_OLD_TIMEVAL_MATCHES_TIMEVAL64
#define __KERNEL_OLD_TIMEVAL_MATCHES_TIMEVAL64 (sizeof (__time_t) == 8)
#endif

To the top of tst-itimer.c.  Sorry I don't have time right now to send a patch
or test this.

-Stafford