AIX port s_lock.h __AIX --> _AIX

Zeugswetter Andreas <andreas.zeugswetter@telecom.at>

From: Zeugswetter Andreas SARZ <Andreas.Zeugswetter@telecom.at>
To: "'pgsql-hackers@hub.org'" <pgsql-hackers@hub.org>
Date: 1998-02-09T13:14:20Z
Lists: pgsql-hackers
I have noticed with delight, that the defined(aix) directives have gone
away (since it is not allways defined),
now there is another one in s_lock.h    __AIX  with two underscores,
wich also is not defined by gcc.
Please use the singel underscore _AIX since it seems to be defined by
all compilers.

Andreas