[lldb] Disable shell tests affected by ld_new bug

lldb/test/Shell/Unwind/eh-frame-dwarf-unwind.test

@@ -1,7 +1,7 @@
 # Test handing of dwarf expressions specifying the location of registers, if
 # those expressions refer to the frame's CFA value.
 
-# UNSUPPORTED: system-windows
+# UNSUPPORTED: system-windows, ld_new-bug
 # REQUIRES: target-x86_64, native
 
 # RUN: %clang_host %p/Inputs/call-asm.c %p/Inputs/eh-frame-dwarf-unwind.s -o %t

lldb/test/Shell/Unwind/thread-step-out-ret-addr-check.test

@@ -2,7 +2,7 @@
 # points to non-executable memory.
 
 # REQUIRES: target-x86_64
-# UNSUPPORTED: system-windows
+# UNSUPPORTED: system-windows, ld_new-bug
 
 # RUN: %clang_host %p/Inputs/call-asm.c -x assembler-with-cpp %p/Inputs/thread-step-out-ret-addr-check.s -o %t
 # RUN: not %lldb %t -s %s -b 2>&1 | FileCheck %s

lldb/test/Shell/lit.cfg.py

@@ -1,5 +1,6 @@
 # -*- Python -*-
 
+import json
 import os
 import platform
 import re
@@ -179,3 +180,18 @@ def calculate_arch_features(arch_string):
 
 if "LD_PRELOAD" in os.environ:
     config.available_features.add("ld_preload-present")
+
+# Determine if a specific version of Xcode's linker contains a bug. We want to
+# skip affected tests if they contain this bug.
+if platform.system() == "Darwin":
+    try:
+        raw_version_details = subprocess.check_output(
+            ("xcrun", "ld", "-version_details")
+        )
+        version_details = json.loads(raw_version_details)
+        version = version_details.get("version", "0")
+        version_tuple = tuple(int(x) for x in version.split("."))
+        if (1000,) <= version_tuple <= (1109,):
+            config.available_features.add("ld_new-bug")
+    except:
+        pass