[llvm] [flang-rt] replace the triple dir to 'aix' for flang-rt to be consistent with clang on AIX. (PR #130875)

[Michael Kruse via llvm-commits]

Meinersbur wrote:

The snippet was copied from https://github.com/llvm/llvm-project/blob/665299eb3e7a142199e2c22eb294c5e01ef1655d/compiler-rt/cmake/Modules/CompilerRTUtils.cmake#L463-L508. Do intend to update it there as well?

https://github.com/llvm/llvm-project/pull/130875