Don't claim GCC predefines __POSIX__

[Joseph S. Myers]

On Fri, 17 Feb 2012, Carlos O'Donell wrote:

> How do you test that you are on a POSIX compliant system?

Practically, run autoconf tests for the features you care about, which are 
unlikely to be 100% conformance.  For 100% conformance, run a conformance 
testsuite - or if anyone does POSIX certification, look at a list of 
certified systems.

-- 
Joseph S. Myers
joseph@codesourcery.com