[patch] Let libstdc++ know that VxWorks has_nanosleep

[Jonathan Wakely]

On 22/12/19 23:20 +0100, Olivier Hainque wrote:
>Hi Jonathan,
>
>> On 19 Dec 2019, at 12:13, Jonathan Wakely <jwakely@redhat.com> wrote:
>>
>>
>> Is there a way to detect that more reliably? Should we replicate the
>> test used later in the file, to detect whether the timers are really
>> enabled for VxWorks?
>>
>>      AC_MSG_CHECKING([for nanosleep])
>...
>> You're the port maintainer though, so if you think that's not needed
>> then the patch is OK for trunk.
>
>Thanks for your feedback Jonathan,
>
>Unfortunately, the AC kind of check is actually less reliable
>on VxWorks, in particular for the so called "kernel" mode where
>linking a "module" actually performs only a partial link to be
>downloaded on a target where the run-time loader takes care of
>the rest.
>
>The current assumption on the environment configuration is on
>a component included by default and required for a number
>of very common time related operations anyway, so always there
>in practice in our experience.
>
>The rare/unlikely users that would not have the library
>configured in on the VxWorks end would just not access to the
>c++ time related facilities, which is not a problem.
>
>Overall, this really seems like a good setting for
>--enable-libstdcxx-time auto.

OK, that makes sense. Thanks!