Add dsymutil as a mac cipd dependency.

This becomes necessary due to [1]. We cannot roll DEPS otherwise [2].
WebRTC is doing this too [3].

[1] https://chromium-review.googlesource.com/c/chromium/src/+/1500198
[2] https://chromium-review.googlesource.com/c/v8/v8/+/1505272
[3] https://webrtc-review.googlesource.com/c/src/+/125840

TBR=machenbach@chromium.org

Change-Id: I07ecc878f6c64767be025c9999dbb49423031e90
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1505292Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60046}

DEPS

@@ -111,6 +111,16 @@ deps = {
       'condition': 'host_cpu != "s390"',
       'dep_type': 'cipd',
   },
+  'src/tools/clang/dsymutil': {
+    'packages': [
+      {
+        'package': 'chromium/llvm-build-tools/dsymutil',
+        'version': 'kykIT8m8YzNqqLP2xFGBTuo0ZtU9lom3BwiStWleyWkC',
+      }
+    ],
+    'condition': 'checkout_mac',
+    'dep_type': 'cipd',
+  },
   'v8/test/wasm-js/data':
     Var('chromium_url') + '/external/github.com/WebAssembly/spec.git' + '@' + '44dfa15cb87b1e9bef36e033ad5d2cdc4c2008fd',
 }