[AIX] Disable empty.ll test using unsupported split dwarf

This test uses split-dwarf feature, which is not currently supported on AIX. Set this test to `UNSUPPORTED` on AIX for now.

Reviewed By: shchenz

Differential Revision: https://reviews.llvm.org/D114567
diff --git a/llvm/test/DebugInfo/Generic/empty.ll b/llvm/test/DebugInfo/Generic/empty.ll
index 40f54c2..4bb5755 100644
--- a/llvm/test/DebugInfo/Generic/empty.ll
+++ b/llvm/test/DebugInfo/Generic/empty.ll
@@ -1,3 +1,4 @@
+; UNSUPPORTED: -aix
 ; RUN: %llc_dwarf < %s -filetype=obj | llvm-dwarfdump -v - | FileCheck %s
 ; RUN: %llc_dwarf -split-dwarf-file=foo.dwo < %s -filetype=obj | llvm-dwarfdump -v - | FileCheck --check-prefix=FISSION %s