[AIX][llvm][support] Implement getHostCPUName

Authored by daltenty on Feb 9 2021, 12:56 PM.


[AIX][llvm][support] Implement getHostCPUName

We implement getHostCPUName() for AIX via systemcfg interfaces since access to the processor version register is a privileged operation. We return a value based on the current processor implementation mode.

This fixes the cpu detection used by clang for -mcpu=native.

Reviewed By: hubert.reinterpretcast

Differential Revision: https://reviews.llvm.org/D95966