Add AIX to the test macro-same-context XFAIL list

[ShuhongL]

Summary

Since the integrated assembly parser was not implemented yet for AIX and macro is not part of the native assembly dialect on AIX, the test macro-same-context is expected to fail for AIX; hence added AIX to XFAIL list.

[jasonliu]

The comment about integrated assembler was not implemented for AIX is not exact correct.
You could still get reasonable object file generation for AIX with -fintegrated-as option turn on.
I think you meant the "assembly parser for AIX is not implemented yet."

[hubert.reinterpretcast]

It may make sense to document in the commit message that .macro is not part of the native assembly dialect on AIX, but either the test would work (and we will update it when lit reports it) or a separate test would be put into place to verify that .macro is diagnosed as not being a valid directive.

[ShuhongL]

added comment: macro is not part of the native assembly dialect on AIX

[daltenty]

LGTM

llvm/test/MC/AsmParser/macro-same-context.ll

 ;; Test that macros in inline assembly blocks share the same context,
 ;; thus a definition is available to the whole file. PR36110
 ; RUN: not llc < %s 2>&1 | FileCheck %s
 ; REQUIRES: default_triple
+;; This test is expected to fail on AIX,
+;; since the integrated assembly parser was not implemented yet for AIX.
+; XFAIL: aix
 
 define void @test() {
   call void asm sideeffect ".macro FOO\0A.endm", "~{dirflag},~{fpsr},~{flags}"() #1
   call void asm sideeffect ".macro FOO\0A.endm", "~{dirflag},~{fpsr},~{flags}"() #1
 ; CHECK: error: macro 'FOO' is already defined
   ret void
 }