Fix cranelift-fuzzgen fuzzer from TrapCode refactoring

This commit fixes an issue found on OSS-Fuzz for the cranelift-fuzzgen
fuzzer which was caused by bytecodealliance#9338 but that PR forgot to fix.

fuzz/fuzz_targets/cranelift-fuzzgen.rs

@@ -107,6 +107,9 @@ impl Default for Statistics {
         // Pre-Register all trap codes since we can't modify this hashmap atomically.
         let mut run_result_trap = HashMap::new();
         run_result_trap.insert(CraneliftTrap::Debug, AtomicU64::new(0));
+        run_result_trap.insert(CraneliftTrap::BadSignature, AtomicU64::new(0));
+        run_result_trap.insert(CraneliftTrap::UnreachableCodeReached, AtomicU64::new(0));
+        run_result_trap.insert(CraneliftTrap::HeapMisaligned, AtomicU64::new(0));
         for trapcode in TrapCode::non_user_traps() {
             run_result_trap.insert(CraneliftTrap::User(*trapcode), AtomicU64::new(0));
         }