Add generated fuzzer files to .gitignore

Hi Brad,

am I right that the two files that I added to .gitignore are generated
by your fuzzer CL (https://codereview.chromium.org/2273303002/)?

Cheers, Andreas

R=bradnelson@chromium.org

Review-Url: https://codereview.chromium.org/2289163002
Cr-Commit-Position: refs/heads/master@{#39021}

.gitignore

@@ -103,3 +103,5 @@ turbo*.cfg
 turbo*.dot
 turbo*.json
 v8.ignition_dispatches_table.json
+/test/fuzzer/wasm.tar.gz
+/test/fuzzer/wasm_asmjs.tar.gz