[wasm] Add a flag to generate an mjsunit test out of a wasm-code fuzzer test case.

src/flag-definitions.h

Index: src/flag-definitions.h
diff --git a/src/flag-definitions.h b/src/flag-definitions.h
index 6654192d805b3dcdaa0ed9d64220ed1924dddfe6..6718886f675b00e08d06074106ea886c1033b42b 100644
--- a/src/flag-definitions.h
+++ b/src/flag-definitions.h
@@ -533,7 +533,8 @@ DEFINE_BOOL(wasm_guard_pages, false,
             "add guard pages to the end of WebWassembly memory"
             " (experimental, no effect on 32-bit)")
 DEFINE_IMPLICATION(wasm_trap_handler, wasm_guard_pages)
-
+DEFINE_BOOL(wasm_code_fuzzer_gen_test, false,
+            "Generate a test case when running the wasm-code fuzzer")
 // Profiler flags.
 DEFINE_INT(frame_count, 1, "number of stack frames inspected by the profiler")
 // 0x1800 fits in the immediate field of an ARM instruction.