[AIX][XCOFF] address post-commit review comments of patch https://reviews.llvm.org/D82549

Summary:
Address post-commit review comments in the https://reviews.llvm.org/D82549, including

changed file name from llvm/test/tools/llvm-readobj/XCOFF/xcoff-auxiliary-header.test --> llvm/test/tools/llvm-readobj/XCOFF/auxiliary-header.test
replaced macro define by using lambda function.
added a helper function to reduce the duplicated check and print error code.

Reviewer : James Henderson
Differential Revision: https://reviews.llvm.org/D116220