update lldb commit hash (#27009)

This brings in the changes from apple/swift-lldb#1961.

Author: marcrasi

utils/update_checkout/update-checkout-config.json

@@ -470,7 +470,7 @@
                 "llvm": "swift-DEVELOPMENT-SNAPSHOT-2019-08-12-a",
                 "clang": "ecfead281dab91cee05d78a5699c72cd3c93b08f",
                 "swift": "tensorflow",
-                "lldb": "1159b66d1b8bfa6fdf7f7aff56479451a3a56339",
+                "lldb": "2d11a3502600c9ceb27c93340b6f7e943477ae8c",
                 "cmark": "swift-DEVELOPMENT-SNAPSHOT-2019-08-12-a",
                 "llbuild": "swift-DEVELOPMENT-SNAPSHOT-2019-08-12-a",
                 "swiftpm": "swift-DEVELOPMENT-SNAPSHOT-2019-08-12-a",