pip install fails on AIX

[shubhamhii]

Closes #160

[arigo]

This fix is likely broken: unless I'm mistaken, it compiles with the warning "no definition for read_barrier(), missing synchronization for multi-thread initialization in embedded mode" and then CFFI can (very rarely) break in case of multithreaded usage. Can you check if __sync_synchronize() is really not defined in your compiler nowadays?

[mattip]

We will need some help to be convinced this PR solves the problem correctly, so more words will help.

Can you check if __sync_synchronize() is really not defined in your compiler nowadays?

Did you check that?

[mattip]

I think the suggestion in issue #197 to check for gcc and use the appropriate __sync_synchronize would be a better localized fix and less magical. Or to go big and relate to #201

[shubhamhii]

Hi,

This fix isn't required anymore. The issue is with aix environment only.
I have added a comment pertaining to it.
#197

Regards,
Shubham