[flang-rt] Using get_toolchain_os_dirname for AIX to get lib path instead of changing get_toolchain_arch_dirname.

Author: DanielCChen

flang-rt/cmake/modules/GetToolchainDirs.cmake

@@ -34,8 +34,9 @@
 function (get_toolchain_library_subdir outvar)
   set(outval "lib")
 
-  if (APPLE)
+  if (APPLE OR (UNIX AND CMAKE_SYSTEM_NAME MATCHES "AIX"))
     # Required to be "darwin" for MachO toolchain.
+    # AIX uses lib/${os_dir} as if LLVM_ENABLE_PER_TARGET_RUNTIME_DIR=OFF
     get_toolchain_os_dirname(os_dirname)
     set(outval "${outval}/${os_dirname}")
   else ()
@@ -118,9 +119,6 @@ function (get_toolchain_arch_dirname outvar)
     set(target "amdgcn-amd-amdhsa")
   elseif("${arch}" MATCHES "^nvptx")
     set(target "nvptx64-nvidia-cuda")
-  elseif(UNIX AND CMAKE_SYSTEM_NAME MATCHES "AIX")
-    # Put at lib/aix to be consistent with clang on AIX.
-    string(TOLOWER "${CMAKE_SYSTEM_NAME}" target)
   else()
     set(target "${arch}${triple_suffix}")
   endif()