Remove workaround for AIX 3.2 crashes

Remove workaround for AIX 3.2 crashes

Emacs does not support AIX 3.2 since 2008.

This workaround for AIX 3.2.3 and 3.2.4 (released in 1992) was
introduced in 1999 and was only active with #ifdef AIX3_2.  In 2008, the
condition was changed to #ifdef AIX when support for these older AIX
versions was dropped. I couldn't find any justification for why this
workaround was retained (instead of being removed) in the commit message
or mailing list archives.

Given that users of AIX 4.0 (released in 1995) or later have not had
this workaround for over a decade (1999-2008), it seems safe to assume
that it is no longer necessary.  Removing it will also prevent the
incorrect overriding of the LANG variable on those systems.

* src/emacs.c [AIX] (main): Remove workaround for AIX 3.2.  (Bug#75153)

(cherry picked from commit 4021b92403ca184bc0cd52f33ed5c6e27780cede)