[libc++][AIX] Add OS version to target triple

This will allow for configuring tests according to AIX version.

Reviewed By: daltenty, #libc, Mordante

Differential Revision: https://reviews.llvm.org/D149660

GitOrigin-RevId: 4fc70197919cded66502d1ad853f9e7f344b9a77
1 file changed