[PATCH, libstdc++] Fix detection of posix_memalig for cross-builds

[Jonathan Wakely]

On 30/11/16 22:32 +0100, Christophe Lyon wrote:
>On 30 November 2016 at 20:00, Bernd Edlinger <bernd.edlinger@hotmail.de> wrote:
>> Hi,
>>
>> I noticed that a cross-compiler produces an unusable libstdc++.so
>> that contains an unresolved reference to aligned_alloc instead of
>> posix_memalign, or whatever is actually available.
>>
>> Therefore it is impossible to link any C++ programs against the
>> libstdc++.so that comes with the cross-compiler.
>>
>> That happens for instance in the following configuration:
>> --target=arm-linux-gnueabihf.
>>
>
>How could this be unnoticed so far?

I did wonder that.

The newlib config is hardcoded, which probably covers a lot of the
cross builds in regular use.

>> The attached patch adds a link test for the memalign function
>> and fixes the cross-build for me.
>>
>> Is it OK for trunk?
>>
>>
>> Thanks
>> Bernd.