[glibc] nptl: Add missing placeholder abi symbol from nanosleep move

[Adhemerval Zanella]

On 07/11/2019 13:54, Florian Weimer wrote:
> * Adhemerval Zanella:
> 
>> https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=4f4bb489e0ddd2f24b2a5d352bb39f8dcdb38050
>>
>> commit 4f4bb489e0ddd2f24b2a5d352bb39f8dcdb38050
>> Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
>> Date:   Thu Nov 7 15:10:35 2019 +0000
>>
>>     nptl: Add missing placeholder abi symbol from nanosleep move
>>     
>>     Adds the __libpthread_version_placeholder symbol with the same version
>>     of nanosleep/__nanosleep that was removed by 79a547b162657b3f and that
>>     is not provided by other symbols.
> 
>> +GLIBC_2.2 __libpthread_version_placeholder F
> 
> Sorry, this fix does not look correct to me.  Since GLIBC_2.2 has
> members (and we can easily detect that), it should not get an additional
> placeholder symbol.
> 
> I think you need to add a symbol alias and another compat_symbol to
> nptl/libpthread-compat.c.

It is not strictly incorrect, although superfluous.  Ideally we would need
to add __libpthread_version_placeholder iff there is no other symbol with
same version already present, however I don't see straightforward to optimize
the symbol creation without adding some compat symbol hacking.

Is there a way to force linker to add the .gnu.version_d from the linker
version map without actually requiring the add this place holder symbol?