Rollup merge of rust-lang#148619 - amy-kwan:amyk/AddLockingFunctions_AIX, r=workingjubilee

Enable std locking functions on AIX

This patch enables the std locking functions on AIX by including AIX on the list of supported targets for the locking functions. Excluding AIX from the std locking functions results to compilation errors such as: ("try_lock() not supported").

Author: Zalathar