[lldb][Darwin] Note why this test is xfail'ed on

jasonmolenda · jasonmolenda · commit 0d0ef58c8fac · 2025-05-07T15:53:30.000-07:00
darwin - due to there not being any eh_frame
instructions for _sigtramp from the system libraries.
diff --git a/lldb/test/Shell/Unwind/signal-in-leaf-function-aarch64.test b/lldb/test/Shell/Unwind/signal-in-leaf-function-aarch64.test
@@ -1,6 +1,8 @@
 # REQUIRES: target-aarch64 && native
 # UNSUPPORTED: system-windows
 # llvm.org/pr91610, rdar://128031075
+
+# Darwin _sigtramp doesn't have eh_frame instruction on AArch64
 # XFAIL: system-darwin
 
 
