[foozzie] Add mock for maximum SharedArrayBuffer

No-Try: true
Bug: chromium:1045795
Change-Id: I8313194bd1b0706291bd6a041d370a0b43215e10
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2020956Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66005}

tools/clusterfuzz/v8_mock_archs.js

@@ -30,6 +30,7 @@
   }
 
   ArrayBuffer = mock(ArrayBuffer);
+  SharedArrayBuffer = mock(SharedArrayBuffer);
   Int8Array = mock(Int8Array);
   Uint8Array = mock(Uint8Array);
   Uint8ClampedArray = mock(Uint8ClampedArray);